taxonID	type	description	language	source
F94187BB0424FF95559EFDE7FA681515.taxon	discussion	This key is adapted from Irwin & Lyneborg (1981), Webb & Irwin (1999), and Webb & Metz (2003) using non-genitalic characters. A few couplets require the differentiation of the sexes. The compound eyes of male therevids in the region treated usually touch dorsally, although in Tabuda and Dichoglena they are narrowly separate, no farther apart than the width of the ocellar tubercle. They are much more widely separate in all females. Females have distinctive acanthophorite spines at the tip of the abdomen; these are short, truncate, and arranged in two fanshaped groups. In the male genitalia, the dorsal, plate-like epandrium is usually apically bifid with the lateral apices pointed and enclosing the often-prominent cerci. Genitalia, especially in males, is sometimes difficult to see because of dense setae.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0424FF96559EF8EEFB501299.taxon	discussion	Acrosathe is a Holarctic and Oriental genus (Webb 2009). Males usually are covered in silver-white hairs, at least on the abdomen. Many species live on coastal sand dunes but others inhabit mountains and are often found on lake beaches and other sandy habitats near water. Webb (2009) gives keys to the males and females of the North American species. Acrosathe otiosa (Coquillett) is the only species of the genus previously recorded from British Columbia and Canada (Webb et al. 2013). All specimens of Acrosathe from British Columbia that we have examined key to A. vialis, based on wing colour and most male genitalic characters. This even includes some specimens identified as A. otiosa by D. W. Webb, the revisor of the genus and author of the species identification key (Webb 2009). In one case, specimens collected at the same place, on the same date, by the same collector were identified as both A. otiosa and A. vialis; males as the former, females as the latter. Acrosathe otiosa and A. vialis are very similar morphologically and distinguishing them is problematic as some of the diagnostic characters are somewhat variable. For the purposes of this study, we include A. vialis as a British Columbia species but also accept A. otiosa because of the identifications of unexamined specimens in databases and the literature. This study is not a revisionary systematic work; we expect future work on the genus will clarify this taxonomic confuseion.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0427FF96559EFDBBFCAF1759.taxon	description	Database and literature records (23). BC: Glenemma; Hornby Island; Nanaimo; Nanaimo, Biological Station; Oliver; Vancouver; Victoria. CASC, SEM, UCRC, USNM. Conservation status. BC: S 4. Distributional notes. The species ranges in southern British Columbia from southeastern Vancouver Island (Nanaimo, Victoria) and the Lower Mainland (Vancouver) east to the Okanagan Valley (Glenemma, Oliver). Based on is range in the northwestern United States, it probably occurs east into British Columbia’s Columbia-Kootenay region. Ecoprovinces and other designations. BC: Georgia Depression, Southern Interior. Range. Cordilleran. Southern British Columbia south to California, Utah, and Colorado (Webb et al. 2013). Biological notes. Flight period: 27 May – 15 July. There is little habitat information in British Columbia, but the species has been collected on a sea beach on Vancouver Island.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0427FF96559EFB7BFEB91469.taxon	description	(Fig. 6) Specimens examined (18). BC: Bowser, D’Arcy, Denman Island, Goldpan Provincial Park, Oliver, Langford, Nicola, Parksville, Saanich, Victoria. DEBU, PFC, RBCM, SEM. Database and literature records (0). iNaturalist records (1). BC: Central Saanich (iNat 84506944, Fig. 6). Conservation status. BC: SNR. Distributional notes. Newly reported for BC and Canada; Seattle, Washington, is the former northernmost locality (Webb 2009). Collected in southern British Columbia from coastal southeastern Vancouver Island (Bowser, Victoria) east to the Thompson (Goldpan Provincial Park), Nicola, and Okanagan valleys (Oliver). Based on its United States range, it likely occurs in the Columbia-Kootenay region. Ecoprovinces and other designations. BC: Georgia Depression, Southern Interior. Range. Cordilleran. British Columbia south through Idaho and Washington to Wyoming, Arizona, and California (Webb et al. 2013). Biological notes. Flight period: 10 May – 4 August. Specimens have been captured on sea beaches and dunes, on river shoreline rocks, in a small peaty fen, and on Garry Oak (Quercus garryana) and Douglas-fir (Pseudotsuga menziesii) trees.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0427FF96559EF8ABFBED14B1.taxon	discussion	Six species of Cliorismia are reported in the Holarctic. There are four Palaearctic species and two in the Nearctic; both of the latter live in western North America (Webb 2003, Webb et al. 2013).	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0426FF97559EFF6AFEA010C9.taxon	description	Database and literature records (105). YT: Burwash Landing, Duke River (type locality); Buxhy Mountain, 15 km S Carmacks; Carcross; Carcross, 3.2 km N; Carmacks; Carmacks, 26 km S; Conglomerate Mountain, 8.8 km S Twin Lakes; Kluane Lake, south end; Kluane Lake, Cultus Bay; Kluane Lake, mi 1054 Alaska Highway; Kluane National Park, Sheep Creek Road; Lapie River at Glacier Creek; Little Salmon Lake, 35 km E; Mayo; Ross River; Stewart Crossing, 6 km NW; Tatchun Lake; Whitehorse. AK: Fairbanks; Richardson Highway, Mile 318. CASC, CNCI, INHS, LEMQ, MEI, SEM, WSUC. iNaturalist records (1). YT: Nisling River (iNat 173331518). Conservation status. YT: S 5 Distributional notes. Cliorismia bussi is a northern species, as yet unknown in British Columbia, but common in the southern Yukon from Kluane Lake and Carcross east to Ross River and north to Mayo. It probably ranges farther north as it occurs at Reindeer Depot in the Northwest Territories. The type locality is near Burwash Landing, Yukon (Webb et al. 2013). Cliorismia bussi is also found in Alaska. Ecoprovinces and other designations. YT: Boreal Cordillera. AK: Beringia Boreal. Range. East Beringian. Alaska east through the Yukon to the Northwest Territories (Webb et al. 2013). Biological notes. Flight period: 28 May – 15 August. The species has been collected in Populus tremuloides parkland, on sand dunes (Fig. 15), along a river shoreline, at a shallow alkaline pond in salt flats, and on dry grassland slopes.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0426FF97559EFB3AFB1C1495.taxon	materials_examined	Specimens examined (44). YT: Carcross; Carcross, Bennett Lake dunes; Kluane National Park, Bullion Creek dunes; Nisling River; Sekulmun Lake, N end; Sekulmun Lake, Isaac Creek; Takhini River dunes 6.8 km NNE Kusawa Lake outlet; Whitehorse, 5 km N. AK: Becharof National Wildlife Refuge; Gates of the Arctic National Park; Kobuk Valley National Park. RBCM, UAM. Database and literature records (93). YT: British Mountains; British Mountains, Firth River (Fig. 14); Carcross; Old Crow; Trout Lake. AK: Kobuk dunes, 145 km E Kotzebue; Nogahabara dunes, 105 km N Galena. CNCI, INHS, MEI, SEM, USNM.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0426FF97559EFB3AFB1C1495.taxon	conservation	Conservation status. Yukon: S 4 S 5	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0426FF97559EFB3AFB1C1495.taxon	distribution	Distributional notes. A Holarctic therevid, D. gorodkovi ranges in the western boreal region in North America. It is unknown in British Columbia but widespread in the Yukon, where it is recorded from scattered localities in the southwest (Carcross, Kluane, Kusawa Lake, Whitehorse) and far north (British Mountains, Old Crow). In Alaska, it inhabits dune systems in the north (Killik River, Kobuk, Nogahabara) and occurs south to the Alaska Peninsula; it probably is widespread in sandy sites over much of the state. Ecoprovinces and other designations. YT: Boreal Cordillera, Taiga Cordillera. AK: Arctic Tundra, Beringia Boreal, Subarctic Tundra. Range. Palaearctic-East Beringian. Russia and China east to Alaska, Yukon, Northwest Territories, and northern Manitoba (Webb & Irwin 1991, Webb et al. 2013, Liu & Yang 2012).	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0426FF97559EFB3AFB1C1495.taxon	biology_ecology	Biological notes. Flight period: 23 May – 25 July. Dialineura gorodkovi is reported in grassland tundra (Fig. 14) and on sand dunes or blowouts near, or away from, water (Fig. 15). One dune site on the Takhini River, Yukon, was sparsely vegetated with Carex sabulosa, Polemonium sp., and Lupinus sp. (RBCM). Specimens were collected from under wood and rocks on a sandy lakeshore in Becharof National Wildlife Refuge, Alaska (UAM).	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0426FF97559EFC12FAA61719.taxon	discussion	The genus Dialineura is Holarctic. All 12 species live in Eurasia; one of them, D. gorodkovi, also occurs in North America. Webb & Irwin (1991) note that species inhabit sand dunes and other sandy areas in boreal regions.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0429FF98559EFF6AFBCA1395.taxon	discussion	Dichoglena is a Holarctic genus (Webb 2003) with one species in each hemisphere.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0429FF98559EFEB6FDC410A5.taxon	description	Database and literature records (11). BC: Princeton, 6.4 km W; Robson; Vernon. YT: LaForce Lake. CNCI, INHS, MEI, SEM. Conservation status. BC: S 4, YT: SU Distributional notes. This fly is uncommon in the southern Interior valleys of British Columbia from the Princeton and Ashcroft areas east through the Okanagan to the Columbia Valley at Robson; it is recorded in the far north at Atlin. Based on records in adjacent jurisdictions, the species is likely widespread over much of the province’s Interior. There are two occurrences in the south-central Yukon (LaForce and Ethel lakes); almost certainly the species ranges throughout the southern Yukon and probably across much of boreal Canada. Ecoprovinces and other designations. BC: Southern Interior, Southern Interior Mountains, Northern Boreal Mountains. YT: Boreal Cordillera. Range. Cordilleran (plus eastern distribution). Yukon and British Columbia east to Ontario and Quebec; Maine south to New Jersey, Pennsylvania, Ohio, Oklahoma, New Mexico, California (Webb et al. 2013). Biological notes. Flight period: 6 March – 21 July. In the region, Dichoglena nigrina has been collected in sandy areas such as beaches and roadsides.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0429FF98559EFBE6FD02153D.taxon	discussion	Ozodiceromyia is a Nearctic and Neotropical genus whose species range from southern Canada to Ecuador (Webb et al. 2013). It is the most species-rich therevid genus in the Americas with many undescribed species (Gaimari & Webb 2009); there are six new species from British Columbia, none of which are known in the Yukon or Alaska. Stephen Gaimari (pers. comm.) notes that O. platancala (Loew) occurs in Alberta and may range into BC, but this has not been verified. The genus name is often misspelled in the literature as “ Ozodiceromya ”. Ozodiceromyia costalis (Loew) was misidentified in the RBCM database and was included in Cannings (2018). Ozodiceromyia levigata (Loew) has been commonly reported from the province but appears to have been misidentified; these specimens represent other closely related, undescribed species widespread in southern British Columbia (Stephen Gaimari, pers. comm.). Localities include Ashcroft, Chilcotin, Clinton, Dog Creek, Gang Ranch, Kamloops, Osoyoos, Penticton, Vaseux Creek, Vernon, Victoria, and Walhachin (BMNH, CNCI, INHS, LACM, MEI RBCM, SEM, USNM). Gaimari & Webb (2009) note that species live in diverse environments from dune systems and deserts to a wide range of forest ecosystems, from shrub steppe and savannas to grasslands. Adults have been collected from shrubs covered in aphid honeydew (Irwin & Lyneborg 1980).	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0429FF99559EF95EFE3D13B8.taxon	materials_examined	Specimens examined (6). BC: Nelway, Pend-d’Oreille Hills; Oliver, UBC Geology Camp. RBCM, SEM.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0429FF99559EF95EFE3D13B8.taxon	discussion	Database and literature records (7). Carquille; Oliver, UBC Geology Camp. CSCA, SEM.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0429FF99559EF95EFE3D13B8.taxon	conservation	Conservation status. BC: S 3 S 4	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0429FF99559EF95EFE3D13B8.taxon	distribution	Distributional notes. Known from three localities in southern Interior of British Columbia, O. nanella is probably widespread in dry forests and grasslands north to about 51 degrees N. Ecoprovinces and other designations. BC: Southern Interior, Southern Interior Mountains. Range. Cordilleran. British Columbia south to California, Arizona, New Mexico; Mexico (Webb et al. 2013).	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0429FF99559EF95EFE3D13B8.taxon	biology_ecology	Biological notes. Flight period: 7 July – 28 July. The species inhabits grasslands and dry forests of all types; dry watercourses, stream sides.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0428FF99559EFEDBFDA21080.taxon	description	Database and literature records (64). BC: Bowser; Christina Lake; Gillies Bay; Oliver; Oliver, UBC Geology Camp; Oliver, 6 km N; Oliver, 11.3 km N; Okanagan Falls; Okanagan Falls, White Lake; Osoyoos; Osoyoos, Richter Pass; Robson; Summerland; Vernon. CNCI, CSCA, EMUS, MEI, SEM, USNM. Conservation status. BC: S 4 Distributional notes. This therevid is recorded in British Columbia from Vancouver Island (Bowser, Nanaimo) east to the Okanagan Valley (Oliver, Vernon) and Columbia River (Robson). Its range probably includes the southern valleys east to the Rocky Mountains and north to the Thompson drainage, based on data from adjacent jurisdictions. Ecoprovinces and other designations. BC: Georgia Depression, Southern Interior, Southern Interior Mountains. Range. Western. British Columbia east to Ontario, south to Texas, New Mexico, Arizona, and California; Mexico (Webb et al. 2013). Biological notes: Flight period: 30 May – 8 October. In British Columbia, O. signatipennis has been collected in a shrub thicket (Rosa woodsii and Crataegus douglasii) in Festuca grassland, in an aspen draw in Pinus ponderosa woodland, and along a sandy lakeshore.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0428FF99559EFBC3FB7F1784.taxon	discussion	The seven species of Pallicephala are Nearctic in distribution. Five live in western North America: three are recorded in the Yukon, two of these in British Columbia. Webb & Irwin (1991) give a key to the species. Pallicephala willistoni (Cole) is considered a synonym of P. pachyceras (Williston) (Webb et al. 2013).	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0428FF99559EFAC7FD3D14B0.taxon	materials_examined	Specimens examined (38). BC: Dewdney; Fort Fraser; Hope, Coquihalla River; Hope, Hunter Creek; Kikomun Creek Park; Tutshi Lake, south end. YT: Aishihik, 7.2 km N; Aishihik Road, km 95; Alaska Highway, km 1800 at Swede Johnson Creek; Albert Creek; Carcross, Bennett Lake dunes (Fig. 15); Kluane Lake, Cultus Bay; Takhini River, Alaska Highway bridge; Upper Laberge. RBCM, ROME.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0428FF99559EFAC7FD3D14B0.taxon	discussion	Database and literature records (9). BC: Chilliwack, Fort Fraser, Grand Forks, Quesnel, Robson. INHS, MEI, SEM, Webb & Irwin (1991).	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0428FF99559EFAC7FD3D14B0.taxon	conservation	Conservation status. BC: S 3 S 5. YT: SNR.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0428FF99559EFAC7FD3D14B0.taxon	distribution	Distributional notes. Pallicephala occidentalis is widespread in British Columbia from the Lower Fraser Valley (Dewdney, Hope) east to the Columbia Valley (Robson), north through the central plateau (Quesnel, Fort Fraser) to the Yukon border (Tutshi Lake). It is common in the southwestern Yukon (Kluane Lake, Carcross, Takhini River). Ecoprovinces and other designations. BC: Georgia Depression, Southern Interior Mountains, Central Interior, Northern Boreal Mountains. YT: Boreal Cordillera. Range. Cordilleran. Yukon and British Columbia south through Washington and Oregon to California (Webb et al. 2013).	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0428FF99559EFAC7FD3D14B0.taxon	biology_ecology	Biological notes. Flight period: 4 May – 11 August. The species has been collected along the edge of a sandy, bouldery stream bed among Populus trichocarpa seedings; in sand dunes (Fig. 15), on sandy, south-facing slopes; in a dry alkaline meadow; on Salix catkins (RBCM).	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB042BFF9A559EFF6AFBA3110D.taxon	description	(Fig. 7) Specimens examined (8). BC: Buttle Lake, Flower Ridge; Hope, Hunter Creek; Parksville. RBCM. Database and literature records (5). BC: Agassiz, Duncan, Vancouver (all as P. willistoni). CNCI, Webb & Irwin (1991). iNaturalist records (1). BC: Lake Cowichan (iNat 51032384, as P. willistoni) (Fig. 7). Conservation status. BC: S 3 S 5. YT: SNR. Distributional notes. In British Columbia, P. pachyceras is uncommon but widespread on the south coast from southeastern Vancouver Island (Buttle Lake, Parksville) east to the Fraser Valley (Hope). Ecoprovinces and other designations. BC: Georgia Depression. Range. Cordilleran. British Columbia south to California (Webb et al. 2013). Biological notes. Flight period: 22 April – 23 August. On riparian sand and dunes.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB042BFF9A559EFD4EFAE31759.taxon	materials_examined	Specimens examined (0).	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB042BFF9A559EFD4EFAE31759.taxon	discussion	Database and literature records (10). YT: Carcross; Carcross, Nares Lake. CNCI, INHS, LEMQ.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB042BFF9A559EFD4EFAE31759.taxon	conservation	Conservation status. YT: SU	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB042BFF9A559EFD4EFAE31759.taxon	distribution	Distributional notes. New to the Yukon. Pallicephala quebecensis is known in the Yukon from three closely adjacent locations in the Carcross area and probably occurs in other dune fields or sandy areas in the territory. Ecoprovinces and other designations. YT: Boreal Cordillera. Range. Boreal. Yukon east through northern Saskatchewan to Québec (Hudson Bay) (Webb & Irwin 1991, Webb et al. 2013).	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB042BFF9A559EFD4EFAE31759.taxon	biology_ecology	Biological notes. Flight period: 16 June – 25 July. The species inhabits dunes and other sandy sites.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB042BFF9A559EFB7AFDF7165D.taxon	discussion	Pandivirilia is Holarctic; the seven Nearctic species are keyed by Webb and Metz (2003). The many specimens identified in some collections as Pandivirilia limata Coquillett are considered conspecific with P. conspicua (Webb & Metz 2003, Webb et al. 2013)	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB042BFF9B559EFA7EFC5B1055.taxon	materials_examined	Specimens examined (43). BC: Ainsworth Hot Springs, 3 mi N; Campbell River; Castlegar; Chilcotin; Cowichan Lake; Good Hope Lake, km 675 Highway 37; Hope; Iskut; Langford; Miracle Beach Provincial Park; Penticton, Madeleine Lake; Robson; Saanich, Ten Mile Point; Smithers; Swan Lake, near Swift River; Tagish Lake; Victoria, Cadboro Bay; Wellington. YT: Alaska Highway, km 1713; Carcross, Carcross, Bennett Lake dunes (Fig. 15); Alsek River dunes; Marsh Lake; Squan Lake; Takhini River dunes, 6.8 km NNE Kusawa Lake outlet. DEBU, PFC, RBCM, ROME, SEM. Database and literature records (237). BC: Canim Lake; Courtenay; Cowichan Lake; Criss Creek; Cultus Lake; Galiano Island; Galiano Island, Spanish Hills; Gillies Bay; Harrison Mills; Horseshoe Bay; Kamloops; Keremeos; Kleanza Creek; Langford; Langley; Lillooet; Lorna; Mill Bay; Nanaimo, Departure Bay; Quadra Island; Robson; Squamish, Diamond Head; Soda Creek; Summerland; Trinity Valley; Vancouver; Vancouver, Stanley Park; Vancouver, University of BC; Vernon; Wellington; West Crescent Valley; West Vancouver; Westwick Lake; Williams Lake, 20 km SW; Wycliffe. YT: Carcross; Dempster Highway, mile 87; Kluane National Park, Sheep Mountain; LaForce Lake; Little Atlin Lake; Pine Lake. AK: Kenai Peninsula, Cooper Landing. BPBM, CASC, CNCI, CSCA, INHS, OSUC, SEM, USNM.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB042BFF9B559EFA7EFC5B1055.taxon	conservation	Conservation status. BC: S 5, YT: S 3 S 4.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB042BFF9B559EFA7EFC5B1055.taxon	distribution	Distributional notes. In British Columbia, P. conspicua is widespread and common from Vancouver Island (Campbell River, Victoria) east through the Thompson and Okanagan valleys (Kamloops, Penticton), West Kootenay (Castlegar, Ainsworth), and north through the Cariboo (Westwick Lake, Williams Lake) to the far North (Iskut, Tagish Lake). The species probably ranges east to the Alberta boundary, based on records in that province. There are several localities in southern Yukon (Kluane Lake, Carcross) and Alaska (Cooper Landing). Pandivirilia conspicua likely has a greater range in southern Yukon and Alaska because the species is transcontinental and somewhat boreal in Canada. Ecoprovinces and other designations. BC: Coast and Mountains, Georgia Depression, Southern Interior, Southern Interior Mountains, Central Interior, Northern Boreal Mountains. YT: Boreal Cordillera, Taiga Cordillera. AK: Hypermaritime Forests. Range. Cordilleran (plus eastern distribution). Alaska and Yukon east to Newfoundland and Nova Scotia, south to Maryland, New Mexico, and California; Mexico (Webb & Metz 2003, Webb et al. 2013).	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB042BFF9B559EFA7EFC5B1055.taxon	biology_ecology	Biological notes. Flight period: 2 May – 12 September. Pandivirilia conspicua has been collected on sand dunes near, or far from, water (Fig. 15); one site on the Takhini River, Yukon, was sparsely vegetated with Carex sabulosa, Polemonium sp., and Lupinus sp.; P. conspicua flew there with Dialineura gorodkovi (RBCM). In the Fraser Valley near Hope, the species was active on the shores of a streambed of sand and boulders among Populus trichocarpa seedings, where it was collected with Pallicephala occidentalis (RBCM). Also found in open Pinus ponderosa- Pseudotsuga menziesii woods, a moist meadow, on beach dunes, and in a light trap. Webb & Metz (2003) report it from habitats as diverse as Sphagnum fens to oak-chaparral woodland.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB042AFF9B559EFC77FD32177D.taxon	discussion	Psilocephala is Holarctic. There are two species, one is Palaearctic and the other is Nearctic. The latter, P. vicina Walker, is common and widespread (Webb 2003).	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB042AFF9D559EFB9FFEBE122D.taxon	description	(Fig. 8) Specimens examined (29). BC: Coldwater River Prov. Park; Cranbrook; Dog Creek; Fort St. John; Masset; Meadow Lake; Quesnel; Smithers; Tlell; Tofino; Vancouver; Vernon. YT: Aishihik River; Carcross; Kluane, Slims River Delta; Whitehorse, E of Schwatka Lake dam; Whitehorse, 20 km N. AK: Fairbanks; Matanuska. DEBU, RBCM, UAM, SEM. Database and literature records (110). BC: Armstrong; Atlin; Cranbrook; Engineer; Fort Nelson; Fort St. John; Grand Forks; Grindrod; Kamloops; Kaslo; Langley; Mission; Nakusp; Oliver; Penticton; Pouce Coupe; Quesnel; Robson; Rolla; Salmon Arm; Smithers; Soda Creek; Summerland; Terrace, Mount Allard; Vancouver; Vancouver, University of BC; Vernon; Victoria. YT: Carcross; Dawson, 22.5 km E; Dempster Highway, km 82; Firth River (Fig. 14); Kluane Lake, Cultus Bay; Old Crow; Old Crow, Bluefish Caves; Minto; Rancheria; Snafu Creek; Whitehorse. AK: Haines; Kuk River, 4.8 km above Omarlik River; Matanuska; Yukon-Koyukuk, The Rapids. CASC, CNCI, DEBU, INHS, MCZC, MEI, OSUC, SEM, USNM. iNaturalist records (2). BC: Nahatlatch Provincial Park (iNat 97392001) (Fig. 8); Peachland, Brenda Lake area (iNat 170347075). Conservation status. BC: S 5. YT: S 5 Distributional notes. Common and widespread throughout British Columbia in locations as diverse as Fort Nelson and Oliver, Psilocephala vicina ranges north throughout the Yukon, from Carcross in the south to the Firth River in the north. In Alaska, records are from the Anchorage and Fairbanks regions, but the species is likely more widespread. Ecoprovinces and other designations. BC: Coast and Mountains, Georgia Depression, Southern Interior, Southern Interior Mountains, Central Interior, Boreal Plains, Taiga Plains, Northern Boreal Mountains. YT: Boreal Cordillera, Taiga Cordillera. AK: Beringia Boreal, Coast Mountains Boreal, Hypermaritime Forests. Range. Transition. Alaska, Yukon, and Northwest Territories east to Newfoundland and Nova Scotia, south to New York, Illinois, Colorado, and California (Webb et al. 2013). Biological notes. Flight period: 13 May – 13 August. The species has been collected on sea and lakeshore dunes (Fig. 15), in Pseudotsuga menziesii / Calamagrostis rubescens woodland, at a meadow edge, and on an open dry grassland slope.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB042CFF9D559EFD76FCB715DF.taxon	description	(Figs. 9, 10) Specimens examined (119). BC: Bennett; Duffey Lake; Eddontenajon Lake; French Creek, Highway 37; Good Hope Lake, Graham Island, Chown River; Graham Island, Delkatla; Graham Island, Rennell Sound; Graham Island, Skidegate; Graham Island, Skonun Point; Graham Island, Yakan Point; Kootenay Lake, Tye Creek; Masset; Nicola, Salmon River; Penticton, West Bench; Tatshenshini Lake; Tatshenshini River, Towagh Creek; Tlell; Tutshi Lake; Wellington, Nanaimo Lakes; Wellington. Wolf Creek. YT: Dezadeash River; Kluane Lake; Kluane National Park, Bullion Creek; La Biche River: Teslin; Upper Liard. DEBU, RBCM, SEM. Database and literature records (82 + 1). BC: Atlin; Dean River; Moresby Island; Queen Charlotte City; Salmon Arm; Summit Lake, mile 392 Alaska Highway; Tunjony Lake. YT: Burwash Flats, 17 km WNW; Carcross; Carmacks; Dempster Highway, km 140.1; Johnson’s Crossing; Kluane, Slims River Delta; Kluane Lake, mile 1054 Alaska Highway; Nahanni Range Road, km 128; Old Crow, 35 km WSW; Otter Lake; Rancheria, 7 km E; Rose Lake, South Canol Road; South Canol Road, km 217.4; Watson Lake. AK: Anchorage; Fairbanks; Kodiak Island, Kukak Bay; Seward; Unalakleet. CASC, CNCI, INHS, SEM, USNM. iNaturalist records (2). BC: Cape Scott (iNat 57752358) (Fig. 9). YT: Teslin (iNat 55078839) (Fig. 10). Conservation status. BC: S 3 S 5, YT: S 4 S 5 Distributional notes. Spiriverpa albiceps is common and reported from scattered localities over most of British Columbia, from Atlin and Summit Lake in the north to Wellington, Penticton, and Kootenay Lake in the south. In the Yukon, locations range from the Dempster Highway in the north to Kluane Lake and Watson Lake in the south; the species is probably distributed over most of territory. It lives over much of Alaska. Ecoprovinces and other designations. BC: Coast and Mountains, Georgia Depression, Southern Interior, Southern Interior Mountains, Northern Boreal Mountains. YT: Boreal Cordillera, Taiga Cordillera, Taiga Plains. AK: Beringia Boreal, Coast Mountains Boreal, Hypermaritime Forests, Subarctic Tundra. Range. Boreal. Western Alaska through the Yukon, east to Newfoundland and Nova Scotia, south to Illinois and New Mexico (Webb et al. 2013). Biological notes. Flight period: 4 June – 20 August. Recorded habitats include sea beach and lakeshore dunes (Fig. 15), river gravel bars and beaches, a spring-fed calcareous fen and a wet herbaceous meadow, a south-facing gravel slope, a gravel pit, and a garden adjacent to grassland.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB042CFF9E559EF900FEAF129E.taxon	description	Database and literature records (33). BC: Courtenay, Udina Bay; Duncan; Hope, Nicolum River; Langford; Mount Currie; Quesnel; Revelstoke; Robson; Shuswap Lake, Cinnemousun Narrows; Vancouver; Vancouver, University of BC. CNCI, OSUC, SEM, ZMAN. Conservation status. BC: S 3 S 4. YT: SNR. Distributional notes. Spiriverpa cinerascens is a widespread species across southern British Columbia from Vancouver Island (Courtenay, Duncan) east to the Columbia River (Revelstoke, Robson) and north to the Cariboo (Quesnel). The species is reported from “ Alaska ” (Webb et al. 2013) but we have found no evidence in the specimens examined, databases, or literature (e. g. Webb 2005) to substantiate this claim. The lack of other northern records suggests that this is an error. Ecoprovinces and other designations. BC: Coast and Mountains, Georgia Depression, Southern Interior, Southern Interior Mountains, Central Interior. Range. Cordilleran. British Columbia south to Arizona and California (Webb et al. 2013). Biological notes. Flight period: 8 April – 20 August. Habitats include dry creek beds (Webb 2005), lakeshores, and streambanks.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB042FFF9E559EFCF1FB741532.taxon	description	(Fig. 11) Specimens examined (42). BC: Chopaka; Monte Lake; Okanagan Falls, White Lake; Oliver, Ripley Lake; Osoyoos, Mud lake; Osoyoos, Strawberry Creek; Osoyoos Lake, Haynes Lease; Penticton; Vaseux Creek; Vaseux Lake (Fig. 16); Vernon. DEBU, RBCM, SEM. Database and Literature records (24). BC: Chopaka; Grand Forks; Kamloops; Oliver; Osoyoos; Osoyoos, Kruger Mountain; Osoyoos, Richter Pass; Nicola; Okanagan Falls; Penticton; Vaseux Lake; Vaseux Lake, hills to E; Vernon. INHS, SEM. iNaturalist records (14). BC: Bighorn; Columbia Gardens; Keremeos; Osoyoos, Kilpoola Lake area; Osoyoos, Spotted Lake; Osoyoos, Haynes Lease; Spences Bridge (e. g., iNat 121543071, 122086201 (Fig. 11), 139358985, 182376315, 206425359). With its large antennae, the species has a distinctive appearance and is readily identified in the field, which accounts for the significant number of iNaturalist records. Conservation status. BC: S 3 S 4 Distributional notes. In British Columbia, Tabuda is probably restricted to dry grassland and forest habitats in the Thompson-Okanagan and Kootenay regions (Chopaka, Spences Bridge, Columbia Gardens north to Kamloops), where it is probably at the northern limit of its range. Ecoprovinces and other designations. BC: Southern Interior, Southern Interior Mountains. Range. Intermontane. British Columbia south to California, Nevada, Utah, Colorado, and Nebraska (Webb et al. 2013). Biological notes. Flight period: 4 April – 24 May. Flight is early; only eight of 68 records are after mid-May and none are later than May. The genus inhabits sandy sites (Irwin & Lyneborg 1980). Records in British Columbia are from mostly lowland sites in sandy grasslands (Purshia tridentata, Artemisia tridentata, Pseudoroegneria spicata habitats) and adjacent open Pinus ponderosa and Pseudotsuga menziesii woods (Fig. 16).	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB042FFF9E559EFDBDFA9A11AE.taxon	discussion	Webb & Irwin (1999) key the six species in the genus. Two species are North American — one eastern, one western. The four Palaearctic species are reported from Kazakhstan, Turkmenistan and nearby countries in central Asia.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB042FFF9E559EF94DFD6F14CE.taxon	discussion	Thereva is widely Holarctic but also lives in parts of the Afrotropical Region (Irwin & Lyneborg 1980, Holston et al. 2007). In the Nearctic it is mostly found in boreal and mountainous habitats. It is by far the most diverse genus in the region under investigation, with 19 species recorded. Thereva species are often collected in woodland; the adults often perch on vegetation and, compared to those of other genera, can be sluggish fliers (Marshall 2012). Holston & Irwin (2005) key the North American species.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB042EFF9F559EFF6AFE5C10CA.taxon	description	Database and literature records (6). BC: Burns Lake; Keremeos, Twin Lakes; Lillooet; Osoyoos, Mount Baldy Summit Road. YT: Whitehorse. CNCI, SEM. Conservation status. BC: S 3 S 4, YT: S 4 Distributional notes. Thereva albopilosa ranges east of the Coast Mountains in British Columbia: Okanagan Valley (Twin Lakes, Oliver), north to Lillooet on the Fraser River, Burns Lake on the central plateau, Peace River region (Fort St. John), and Bennett Lake near the Yukon border. As the species occurs in the Yukon and the Alberta Rockies, it certainly ranges throughout the valleys, plateaus and mountains of most of British Columbia east of the Coast Mountains. In the Yukon, known locations are in the southwest (Kluane, Whitehorse, Sulphur Lake). Ecoprovinces and other designations. BC: Southern Interior, Central Interior, Northern Boreal Mountains, Boreal Plains. YT: Boreal Cordillera. Range. Cordilleran. Southern Yukon south through British Columbia and Alberta to Nevada and New Mexico (Webb et al. 2013). Biological notes. Flight period: 15 June – 29 July. Thereva albopilosa has been collected in a small grassland adjacent to Pinus contorta woods, on sand dunes with sparse Pinus contorta and moss / lichen crust / Arctostaphylos uva-ursi ground cover, in a rich marl fen, and on a roadside rock outcrop. Forest and steppe habitats are the norm (Holston & Irwin 2005).	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB042EFF9F559EFC0AFAB81421.taxon	materials_examined	Specimens examined (33). BC: Alexandria; Arrow Lakes, Burton; Hope, Hunter Creek; Kamloops; Kamloops, Mount Lolo; Kilpoola Lake; Lac du Bois; Okanagan Falls, White Lake; Osoyoos; Osoyoos, Mt. Kobau (Fig. 17); Penticton, West Bench; Robson; Saanich, Rithet’s Bog; Spaist Mountain, Pimainus Lakes; Vernon, Becker Lake; Vernon, Cosen’s Bay. RBCM.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB042EFF9F559EFC0AFAB81421.taxon	discussion	Database and literature records (33). BC: Aspen Grove; Christina Lake; Cranbrook; Fernie, Kamloops, Lac la Hache; Manning Park, Blackwall Peak; Oliver; Pass Creek; Robson; Trinity Valley; Victoria; Victoria, Gordon Head. YT: Snafu Creek, Whitehorse. CASC, CNCI, MEI, OSUC, SEM.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB042EFF9F559EFC0AFAB81421.taxon	conservation	Conservation status. BC: S 4, YT: SU	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB042EFF9F559EFC0AFAB81421.taxon	distribution	Distributional notes. Thereva aurofasciata is relatively common across southern British Columbia, from Vancouver Island (Victoria) east to the Okanagan (Oliver, Vernon) and the East Kootenay (Cranbrook, Fernie), north to the Thompson Valley (Kamloops) and Cariboo (Lac la Hache). The species is probably more widespread in northern areas of the province because it is recorded from the southern Yukon (Whitehorse, Snafu Creek). Ecoprovinces and other designations. BC: Georgia Depression, Southern Interior, Southern Interior Mountains, Central Interior. YT: Boreal Cordillera. Range. Cordilleran. Yukon south through British Columbia and Alberta to California, Arizona, and New Mexico (Webb et al. 2013).	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB042EFF9F559EFC0AFAB81421.taxon	biology_ecology	Biological notes. Flight period: 15 May – 18 August. The species has been collected in Artemisia / Pseudoroegneria grassland; open Pinus ponderosa / Pseudotsuga menziesii / Populus tremuloides woodland; an aspen draw in Pinus ponderosa woodland; and a fen with grasses, sedges, Salix, and Spiraea. Sites range from lowland habitats to subalpine meadows (Fig. 17). Holston & Irwin (2005) give typical locations as “ forest and steppe habitats ”.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0430FF81559EFF6AFEFC1031.taxon	description	(Fig. 12) Specimens examined (15). BC: Cathedral Provincial Park, Glacier Lake; Cathedral Provincial Park, Quinescoe Mountain summit; Hope, Nicolum River; Manning Provincial Park, Strawberry Flats; Nicola; Saanich, Mount Newton; Victoria, Ten Mile Point; Wellington. DEBU, RBCM, SEM. Database and literature records (44 + 4). BC: Agassiz; Chase; Courtenay; Cultus Lake Provincial Park; Dean River; Gabriola Island; Gillies Bay; Hornby Island, Norman Point; Merritt, Midday Valley; Mesachie Lake; Mission; Nanaimo; Quadra Island; Vancouver; Vancouver, University of BC; Victoria (type locality); Wellington. CASC, CNCI, EMEC, INHS, MCZC, MEI, NHMW, OSUC, OSUO, SEM. iNaturalist records (1). Tipella, Harrison Lake, north end (iNat 53228675) (Fig. 12). Conservation status. BC: S 4 Distributional notes. In British Columbia, T. brunnea is widespread in coastal areas (Victoria, Vancouver, Dean River) and the southwestern Interior (Chase, Merritt). It is especially frequent on the south coast and likely occurs east to the Rocky Mountains based on records in adjacent jurisdictions (Holston & Irwin 2005). Ecoprovinces and other designations. BC: Coast and Mountains, Georgia Depression, Southern Interior, Southern Interior Mountains. Range. Cordilleran. British Columbia and Alberta south to Montana and California (Webb et al. 2013). Biological notes. Flight period: 4 May – 6 September. Thereva brunnea is found from sea beaches to alpine meadows.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0430FF81559EFC52FCCB1542.taxon	description	Database and literature records (24). BC: Cariboo, Springhouse; Chilcotin; Chilcotin Ranges; Kamloops; Keremeos; Lac la Hache, Provincial Park; Lac la Hache, Crystal Springs Campsite; Lillooet; McQueen Lake; Oliver, UBC Geology Camp; Quesnel; Soda Creek. CASC, CNCI, EMEC, MEI, SEM. Conservation status. BC: S 4 Distributional notes. In British Columbia, T. cingulata is not known on the Coast; it is widespread in the southwestern Interior (Osoyoos, Ashcroft, Kamloops), north to the Cariboo-Chilcotin (Lac la Hache, Soda Creek, Ilgatchuz Mountains) and Peace River Region (Fort St. John). The species probably occurs east into the southern Rockies, based on Alberta and Montana distribution (Webb et al. 2013). Ecoprovinces and other designations. BC: Southern Interior, Central Interior, Boreal Plains. Range. Cordilleran. British Columbia east to Saskatchewan, south to New Mexico and Arizona (Webb et al. 2013). Biological notes. Flight period: 18 June – 6 September. The fly has been collected in Pseudotsuga menziesii / Calamagrostis rubescens woods, subalpine woodland (Fig. 17), and grassland / Pinus ponderosa parkland interface. Forest and steppe habitats are usual (Holston & Irwin 2005).	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0430FF82559EF98AFB9D122D.taxon	description	Database and literature records (13). BC: Fort St. John; Quesnel; Soda Creek. YT: Minto Landing. CASC, SEM. Conservation status. BC: S 3 S 4, YT: SU Distributional notes. Only three localities are known in British Columbia for T. duplicis, two in the Cariboo (Quesnel, Soda Creek) and one in the Peace River region (Fort St. John). Probably the species ranges extensively in the North, based on records in the Yukon, Northwest Territories, and Alberta (Webb et al. 2013). Thereva duplicis is mostly a species of the Great Plains but extends west into the Cordillera and east in the boreal forest as far as Ontario. There is one record in the central Yukon (Minto Landing). Ecoprovinces and other designations. BC: Central Interior, Boreal Plains. YT: Boreal Cordillera. Range. Great Plains. Yukon and Northwest Territories east to Ontario, south to Michigan, Minnesota, South Dakota, Wyoming, and Montana (Webb et al. 2013). Biological notes. Flight period: 25 June – 29 July. Thereva duplicis mainly lives in mixed or broadleaf woodland (Holston & Irwin 2005) but also has been recorded in boreal forest and prairie habitats.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0433FF82559EFE73FCBA17F1.taxon	description	Database and literature records (94). BC: Adams Lake; Anarchist Mountain; Aspen Grove; Clinton, Porcupine Creek; Cranbrook; Elko; Fife; Hedley; Kamloops; Keremeos, Twin Lakes; Keremeos Creek, 1 km N Highway 3 A; Lillooet; Osoyoos; Osoyoos, Mount Baldy Road; Robson; Robson, Waldie Road; Rock Creek; Similkameen; Vernon; Vernon, Vernon Hill; Yale. CASC, CNCI, CUIC, EMEC, OSUC, SEM. iNaturalist records (1). BC: Okanagan Falls, White Lake (iNat 55185825). Conservation status. BC: S 5 Distributional notes. There are few records of Thereva egressa on the British Columbia coast (Victoria, Koksilah River) but it is common in the southern Interior from the Similkameen drainage (Aspen Grove, Keremeos Creek) east through the Okanagan (Osoyoos) and Boundary region (Fife, Rock Creek) to the Rocky Mountains (Elko). It is recorded north to the Thompson Valley (Adams Lake, Kamloops) and the Peace River region (Wapiti Lake). Ecoprovinces and other designations. BC: Georgia Depression, Southern Interior, Southern Interior Mountains, Central Interior, Sub-boreal Interior, Boreal Plains. Range. Cordilleran. Southern British Columbia and Alberta south to California, Arizona, and Colorado (Webb et al. 2013). Biological notes. Flight period: 12 May – 31 July. Thereva egressa has been collected in the alpine zone in northeastern British Columbia and in regenerating Tsuga heterophylla / Thuja plicata forest on Vancouver Island. Forest and steppe habitats are typical (Holston & Irwin 2005).	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0433FF82559EFB13FD81146D.taxon	description	Database and literature records (15). BC: Vancouver Island, Brooks Peninsula, Cape Cook Lagoon. CNCI, MEI, SEM. Conservation status. BC: S 3 S 4 Distributional notes. Thereva elizabethae is known from only one location in British Columbia: the upper beach sand at Cape Cook Lagoon, Brooks Peninsula, on the northwest coast of Vancouver Island (Fig. 18). It probably occurs on other suitable beaches, at least on the south coast. Ecoprovinces and other designations. BC: Coast and Mountains. Range. Pacific Coast. Southwest British Columbia south to California along the Pacific Coast (Webb et al. 2013). Biological notes. Flight period: 2 – 13 August from a single site (1981). Thereva elizabethae lives on upper beaches and dunes along the Pacific coast (Holston & Irwin 2005) (Fig. 18). Suitable habitat is scattered but widespread on the British Columbia coast.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0433FF83559EF8AFFCFA12E4.taxon	description	Conservation status. BC: SU Distributional notes. BC. The species is recorded from two localities in the BC southern Interior, Seton Lake in the west and Robson in the east. Holston & Irwin (2005) give only the Seton Lake record (CNCI), although Holston apparently identified the two Robson specimens in the SEM. Ecoprovinces and other designations. BC: Southern Interior, Southern Interior Mountains. Range. Cordilleran. Southern British Columbia south to California, Arizona, and Colorado (Webb et al. 2013). Biological notes. Flight period: 2 August – 6 August.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0432FF83559EFE27FEF51615.taxon	description	Database and literature records (31). BC: Bear Lake, London Hill Mine; Cathedral Provincial Park, Glacier Lake Trail; Cathedral Provincial Park, Quiniscoe Mountain summit; Hedley; Moosehorn Lake; Mount Begbie; Robson; Summit Lake, mile 392 Alaska Highway; Tunjony Lake. YT: Carcross; Dempster Highway, km 155; Nahanni Range Road. CNCI, MEC, SEM, USNM. Conservation status. BC: S 5, YT: S 3 S 5 Distributional notes. Thereva foxi is fairly common in the highlands of the southern interior (Mount Begbie; Cathedral Provincial Park), north through the central plateaus and mountains (100 Mile House; Tweedsmuir Provincial Park; Shelagyote Peak) and the Peace River region (Fort St. John) to the far north (Atlin, Summit Lake, Tatshenshini Lake). In the Yukon, the species is recorded from Carcross and Nahanni Range Road in the south to km 155, Dempster Highway, in the north. Ecoprovinces and other designations. BC: Coast and Mountains, Southern Interior, Southern Interior Mountains, Central Interior, Sub-boreal Interior, Boreal Plains, Northern Boreal Mountains. YT: Boreal Cordillera, Taiga Cordillera. Range. Cordilleran. Northern Yukon south through British Columbia and the Alberta Rocky Mountains to Oregon, Utah, and Colorado. (Webb et al. 2013). Biological notes. Flight period: 22 June – 29 August. Thereva foxi is mostly found in mountain habitats such as subalpine meadows and alpine tundra. At Tatshenshini Lake, T. foxi was collected in a lush, wet, herbaceous meadow between alder thickets (RBCM). The species also inhabits dry grassland slopes (Fig. 19) and sand dunes (Fig. 15).	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0432FF84559EFA37FB171394.taxon	description	Database and literature records (3). BC: Merritt; Oliver. CNCI. Conservation status. BC: S 3 S 4 Distributional notes. In British Columbia, Thereva fucata is reported from only the south coast (Victoria, Bute Inlet) and southern Interior valleys (Merritt, Osoyoos, Robson). Ecoprovinces and other designations. BC: Georgia Depression, Coast and Mountains, Southern Interior, Southern Interior Mountains. Range. Cordilleran. British Columbia south to California and Utah; Mexico, Baja California (Webb et al. 2013). Biological notes. Flight period: 2 June – 27 September. In BC, T. fucata is often found in sandy areas; in the Interior, these localities are usually in, or near, grasslands at a variety of elevations (Fig. 17). The species is reported in ground emergence traps in a Larix occidentalis plot in a Vernon forestry seed orchard (RBCM).	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0435FF84559EFEBBFE5C10CD.taxon	description	Database and literature records (169). BC: Comox Lake; Courtenay, Udina Bay; Departure Bay; Diamond Head; Lillooet; Merritt; Nakusp, 23 km N; Nicola; Oliver; Oyama; Penticton; Robson; Salmon Arm; Savary Island, Summerland, Fish Lake; Trinity Valley, Victoria. CNCI, SEM. Conservation status. BC: S 5 Distributional notes. Thereva fucatoides is common over much of southern British Columbia from Vancouver Island (Courtenay, Departure Bay), east through the Nicola (Merritt) and Okanagan (Oyama, Summerland) valleys to the West Kootenay (Nakusp, Robson), and north to the Thompson and Fraser watersheds (Salmon Arm, Lillooet). Ecoprovinces and other designations. BC: Georgia Depression, Coast and Mountains, Southern Interior, Southern Interior Mountains. Range. Cordilleran. British Columbia and Montana south to California, Utah, Colorado (Webb et al. 2013). Biological notes. Flight period: 10 May – 7 October. The species is a relatively late flier; of 174 specimens, only seven were recorded before August. In the United States, T. fucatoides is reported mostly in forest or steppe habitats, mostly in the Coast and Cascade / Sierra ranges. This is one of the most commonly collected therevids in the Nearctic (Holston & Irwin 2005).	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0435FF84559EFC13FCC616F8.taxon	description	Database and literature records (5). BC: Hornby Island, Norman Point; Saanich; Vancouver, University of BC. CNCI, SEM. iNaturalist records (1). BC: Nanaimo (iNat 54120396). Conservation status. BC: S 3 S 4 Distributional notes. In British Columbia, Thereva johnsoni localities are restricted to the south coast. Ecoprovinces and other designations. BC: Georgia Depression. Range. Cordilleran. British Columbia south to Utah and California; Mexico, Baja California (Webb et al. 2013). Biological notes. Flight period: 27 February – 6 August.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0435FF84559EFA1BFEED1494.taxon	description	Database and literature records (27). BC: Lac la Hache; Lytton; Quesnel; Robson; Robson, Waldie Road; Trinity Valley. CNCI, MEI, SEM. iNaturalist records (1). BC: Windermere Lake Park (iNat 30824488). Conservation status. BC: S 3 S 5, YT: SNR. Distributional notes. Thereva krafti is found in scattered localities across the southern interior (Lytton, Trinity Valley) east to the upper Columbia River Valley (Windermere Lake), and north to the Cariboo region (Lac la Hache, Quesnel). Ecoprovinces and other designations. BC: Southern Interior, Southern Interior Mountains, Central Interior. Range. Cordilleran. British Columbia, and Alberta south to California and New Mexico (Webb et al. 2013). Biological notes. Flight period: 20 June – 16 August. Holston & Irwin (2005) state that T. krafti usually inhabits forest and steppe, especially in mountains. At Windermere Lake, a female was killed by a Machimus robber fly (iNat 30824488).	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0434FF85559EFF6AFAB3110D.taxon	description	Database and literature records (65). BC: Robson (type locality), Vernon. CASC, CNCI, KCH, MEI, SEM. Conservation status. BC: S 3 S 4 Distributional notes. In southern British Columbia, T. kristinae is known from Vancouver Island (Savary Island in Georgia Strait) east to the Okanagan (Vernon) and West Kootenay (Robson). Ecoprovinces and other designations. BC: Georgia Depression, Southern Interior, Southern Interior Mountains. Range. Cordilleran. British Columbia south to Nevada and California; Mexico, Baja California (Webb et al. 2013). Biological notes. Flight period: 25 July – 29 August. Sixty-six of the 69 specimens reported here come from Robson (ten years, not consecutive), giving a good estimate of the species’ flight period at a single locality.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0434FF85559EFD4EFC331711.taxon	description	Database and literature records (4). BC: Cathedral Provincial Park, Lakeview Mountain; Moosehorn Lake. CNCI, SEM. Conservation status. BC: SU Distributional notes. Thereva macdunnoughi is recorded from scattered localities in the extreme south of British Columbia (e. g., Whistler) and north (Atlin) of the province. Ecoprovinces and other designations. BC: Coast and Mountains, Southern Interior, Northern Boreal Mountains. Range. Cordilleran. British Columbia and Alberta south to California and Colorado (Webb et al. 2013). Biological notes. Flight period: 27 June – 31 July. Mountain habitats.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0434FF85559EFB32FD22141D.taxon	description	Database and literature records (11). BC: Cloverdale; New Westminster; Vancouver; Vancouver, Point Grey; Vancouver, University of BC. CNCI, KCH, MEI, TAMU, USNM. iNaturalist records (4). BC: Delta (iNat 219882783), Lantzville (iNat 233342721); Richmond (iNat 214675887), Victoria (iNat 169319936). Conservation status. BC: SNA Distributional notes. Thereva nobilitata is the only alien therevid known in British Columbia. It was originally introduced to the Vancouver area from Europe, where it is common (Holston & Irwin 2005). It is also recorded from southern Vancouver Island. The first BC record we have seen is from New Westminster in 1969 (MEI). Ecoprovinces and other designations. BC: Georgia Depression. Range. Introduced. Palaearctic, where it is native. In North America, it is also known from Ontario and Washington State (iNaturalist). Biological notes. Flight period: 6 May – 5 August. This introduced therevid is typical of urban and suburban habitats in extreme southwestern British Columbia.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0437FF86559EFF6AFD1A119E.taxon	description	Database and literature records (5). BC: Cornbeef Creek; Dease Lake. YT: Dempster Highway, km 140.1; White Mountains, Erebia Creek. CNCI, NFRC, RBCM, SEM. Conservation status. BC: S 3 S 4, YT: SU Distributional notes. Thereva strigipes is known in British Columbia from two locations: Dease Lake in the far North and Cornbeef Creek in the Kootenays. Probably the species is widespread throughout most of the Interior as it occurs in adjacent Yukon, Alberta, and Northwest Territories. There are two localities in the northern Yukon from the Dempster Highway and the White Mountains. Ecoprovinces and other designations. BC: Southern Interior Mountains; Northern Boreal Mountains. YT: Taiga Cordillera. Range. Transition. British Columbia, Yukon, and Northwest Territories east to Nova Scotia; south to New Hampshire, New York, and Minnesota (Webb et al. 2013). Biological notes. Flight period: 4 July – 26 July. Thereva strigipes lives mostly in lower elevation mixed and deciduous woodland, especially in the East and on the Great Plains. However, it lives in boreal and subarctic habitats in the far Northwest (Holston & Irwin 2005).	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0437FF86559EFCBEFBD51519.taxon	description	Database and literature records (71). BC: Atlin; Grand Forks; Hudson’s Hope; Kamloops; Keremeos; Lillooet; Merritt, Midday Valley; Mount Revelstoke; Osoyoos; Robson; Seton Lake; Taylor; Telegraph Creek. YT: Alaska Highway, 13.1 km W Takhini River; Carcross; Christmas Creek, km 1688 Alaska Highway; Kluane Lake, Emerald Island; Kluane National Park, Mount Wallace; Kluane National Park, Sheep Creek Road; Kluane National Park, Sheep Mountain; Ross River; Stewart Crossing; Takhini; Tatchun Lake; Whitehorse. CASC, CNCI, LEMQ, MEI, SEM. Conservation status. BC: S 5. Yukon: S 3 S 5 Distributional notes. Thereva utahensis is widespread in the British Columbia interior from the United States border north to Atlin and the Peace River region. It is common in the central and southern parts of the Yukon from Kluane Lake east to Carcross and Ross River, and north to the Stewart Crossing region. The species is probably distributed farther east based on locations in the British Columbia Peace River region. Ecoprovinces and other designations. BC: Southern Interior, Southern Interior Mountains, Central Interior, Boreal Plains, Northern Boreal Mountains, YT: Boreal Cordillera. Range. Cordilleran. Yukon, British Columbia, and Alberta south to California, Utah, and Colorado (Webb et al. 2013). Biological notes. Flight period: 4 June – 26 September. Thereva utahensis lives in various habitats, including sand dunes (Fig. 15), grasslands (Fig. 19), and subalpine environments (Fig. 17).	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
F94187BB0437FF87559EF93AFDFC177D.taxon	description	(Fig. 13) Specimens examined (28). BC: Whistler, Olympic Park. YT: Bear Creek Summit, Mt. Decoeli Trail; Caribou Mountain; Dempster Highway, North Fork Pass; Dempster Highway, km 562; Kathleen River; Klondike Hwy, Moose Creek campground; Kluane National Park, Kaskawulsh River. AK: Anchorage; Anchorage, Triangle Lake; Bettles; Fairbanks, Moose Creek Bluff; Matanuska. RBCM, ROME, UAM, SEM. Database and Literature records (33 + 10). BC: Adams Lake; Atlin; Atlin, Warm Springs; Barkerville; Cathedral Provincial Park, Lake of the Woods trail; Chilkat Pass; Hope Mountains; Kamloops; Kaslo; Lisadele Lake; Radium; Summit Lake, Mile 392 Alaska Highway. YT: Carcross, 3.2 km N; Haines Junction; LaForce Lake; Minto Landing; Richardson Mountains, 66.03 ˚ N; Teslin Lake, 16.1 km NW (type locality). AK: Cooper Landing; Fort Yukon; Kenny Lake; Matanuska; Moose Pass; Palmer; Skagway; Tazlina; Valdez. CASC, CMVH, CNCI, EMEC, MEI, OSUC, ROME, SEM, UMSP, USNM, WSUC. iNaturalist records (2). BC: Coppercrown Mountain (iNat 55120458). YT: Whitehorse (iNat 52909455, Fig. 13). Conservation status. BC: S 5, YT: S 4 S 5 Distributional notes. Thereva webbi is widespread and common in the Interior of British Columbia from Chilkat Pass and Atlin east to Summit Lake (Alaska Highway) south to Whistler, Kamloops, Kaslo, and Radium. It probably occurs over the entire province in, and east of, the Coast Mountains. In the Yukon, the species is widespread and common from Haines Junction east to Teslin Lake, north to the northern Richardson Mountains, but is likely distributed over much of the territory. It is recorded from central (Bettles, Fairbanks) to southern (Anchorage, Kenai) Alaska. Ecoprovinces and other designations. BC: Coast and Mountains, Southern Interior, Southern Interior Mountains, Central Interior, Northern Boreal Mountains. YT: Boreal Cordillera, Taiga Cordillera. AK: Beringia Boreal, Coast Mountains Boreal, Hypermaritime Forests. Range. Boreal. British Columbia, Yukon, and Northwest Territories and east, in the far North, to Manitoba and Labrador; south in the West to Oregon, Utah, and Colorado (Webb et al. 2013). Biological notes. Flight period: 1 June – 7 August. Thereva webbi lives in mixed and deciduous woodland as well as mountain and arctic tundra habitats (Holston & Irwin 2005). In northern British Columbia, the species was found at Atlin, at warm springs in meadow / boreal forest habitat. In the Yukon, it was collected in Salix scrub, dry grassland slopes, and on dunes; in Alaska, on a lawn with Taraxacum plants and in black spruce muskeg with adjacent meadows and dry areas.	en	Gibson, Joel F., Cannings, Robert A. (2025): The Stiletto Flies (Diptera: Therevidae) of British Columbia, Yukon, and Alaska. Zootaxa 5618 (4): 481-508, DOI: 10.11646/zootaxa.5618.4.2, URL: https://doi.org/10.11646/zootaxa.5618.4.2
