Necrobia ruficollis (Fabricius, 1775)

Chapman, Eric G., Leavengood, John M. & Dupuis, Julian R., 2025, The Cleridae and Thanerocleridae of eastern North America, with illustrated keys, updated distributions, and special emphasis on the Kentucky fauna, Zootaxa 5639 (1), pp. 1-88 : 46-47

Necrobia ruficollis (Fabricius, 1775) ; Cleridae : Korynetinae (no tribal assignment)

Illustrations: Plate 3-A. Key to clerid genera, couplet 9-C; Necrobia key, couplet 1-C

Distribution: ME to GA to south TX to southern CA to AK (GBIF data). Most of these records are coastal suggesting multiple introductions through ports. Native to the Palaearctic; adventive and transcontinental in North America . Also reported from Brazil and Argentina.

Natural History: Commonly known as the red-shouldered ham beetle (ESA official common name), Knull (1951) reported this species is associated with bones and skins of carrion where it is both predaceous and saprophagous. Scott (1919) observed that it is attracted to moldy cheese and that larvae are usually saprophagous (e.g., on dead adult flies), but will prey on other insect larvae. This species pupates in pre-existing cavities (e.g., empty fly puparia) where they seal the opening with a white secretion, or they make a pupal cell and line it with this secretion ( Scott, 1919). Papp (1959) added that it feeds on Diptera larvae in carrion and can be a pest in dry fish. Leavengood (2008b) reported that it has been found in bonemeal in two separate shipments. Based on label data, Dorshorst & Young (2008) reported a series of eight specimens collected from “feed in Rennet” (enzymes that curdle milk) in Wisconsin.

Mimicry: Thought to be a chrysomelid mimic (Menier 1985).