Rapala manea (Hewitson, 1863)

Banerjee, Debdulal, Singhamahapatra, Aniruddha & Roy, Subhajit, 2023, New larval host plants for three butterfly (Lepidoptera, Papilionoidea) species from Rahr region of West Bengal, India, Journal of Insect Biodiversity and Systematics 9 (1), pp. 67-79 : 73-74

Rapala manea (Hewitson, 1863)

Common name: Slate Flash ( Fig. 3) ( Table 4)

Biology. A larva was observed and collected by the first author on 17 th December 2020 on Mallotus repandus from a bush beside a pond near the crematorium in Laudoha village (S2). Ovate-triangular leaves of the woody climber was an important key to its identification ( Hooker, 1887; Balakrishnan & Chakrabarty, 2007). The around 4m long climbing shrub, having characteristic thorns on its trunk, was blooming with racemose inflorescence. The larva was provided with young shoots from the host plant until it went into pre-pupation on 25 th December 2020. Early instars of the larva bore into flowers or buds ( Fig. 3C) and fed on the softer parts from inside. The colour and cryptic markings of the larvae are variable and depends on the background colour (van der Poorten & van der Poorten, 2016). They were regularly attended by Crematogaster ants. The pupa was eventually formed on 28 th December 2020. The adult finally eclosed after around 25 days of pupal period on 21 st January 2021. A couple of spherical, pale greenish white eggs ( Fig. 3B) were also later collected by the author by moving the buds apart, within which the eggs were concealed. Though the larvae later emerged from those eggs, however, they could not be traced later, indicating escape or predation. All the larvae were found during winter (November to January), which is the flowering season of the shrub in the region.

Behaviour. The early instars of the larva camouflage themselves by resting on the buds and axils of the inflorescence ( Fig. 3C), coming to the leaves only to change instar ( Fig. 3E). Like most Lycaenid larvae, they too have strong mutualistic association with ants. This host plant is also known as a larval food plant of Mahathala ameria ( Robinson et al., 2010; Kunte et al. 2022), which is also found in this region. However, the first author noticed, the larvae of Mahathala ameria rolls them within the leaves of the plant, and are found in plant individuals, not during the flowering periods. Thus, though Rapala manea and Mahathala ameria share the same host plant, they live in different niches. Larvae were found to rest on axils of the flowers well camouflaged ( Fig. 3E) and comes to leaves only to change instar.

Distribution. Rapala manea is distributed throughout most of the Oriental region (south and south-east Asia), except Taiwan. Within Indian subcontinent, it is distributed throughout excepting the arid regions. In Gangetic plains and western plateau region (and in the Himalayan foothills) of West Bengal too, the adult butterfly is a common visitor often encountered singly perching or nectaring on flowers of bushes.