Smyrna blomfildia

Abstract: Predator avoidance strategies of lepidopteran larvae include morphological traits, such as scoli, spines, and hairs (Frost, 1959), chemical defence, such as unpalatability (Brower, 1984), camou ̄age and mimicry (Edmunds, 1974), myrmecophily (Malicky, 1970; DeVries, 1991), and behavioural traits, including gregariousness, leaf folding and rolling, mining, regurgitating, suspending by silken threads, hiding, resting on island-like leaf segments, and constructing frass chains (Heads & Lawton, 1985; Costa et al., 1992; Freitas & Oliveira, 1992, 1996; Stamp & Casey, 1993; Loef ̄er, 1996; Salazar & Whitman, in press). Frass chains are stick-like structures formed by fecula and silk where the larvae rest when not feeding, which provide an ef®cient refuge against walking arthropod predators by isolating the larvae from the leaf blade when not feeding (Freitas & Oliveira, 1996). The construction of frass chains by early-instar larvae is a widespread behaviour among the nymphalid butter ̄ies in the subfamilies Eurytelinae, Charaxinae, Limenitidinae, and the tribe Coloburini (Nymphalinae) (Muyshondt, 1973a,b,c, 1974, 1976; Muyshondt & Muyshondt, 1976, 1978; Casagrande & Mielke, 1985; DeVries, 1987; Aiello, 1991; Freitas & Oliveira, 1992). Although Freitas and Oliveira (1996) suggested that frass chains might not necessarily have evolved as a response to predation on ant-visited host plants, the behaviour of resting or taking refuge on these structures diminished larval predation or removal by ants. Smyrna blom®ldia Fabricius (Nymphalidae: Coloburini) is a non-myrmecophilous butter ̄y, the larvae of which feed on Urera baccifera (L.) Gaudich. (Urticaceae), a nettle found commonly in secondary environments such as forest edges and gaps, especially in shaded places. Females lay eggs on many parts of the plant including shoot tips, mature and new leaves, and even spines on the stem near the apical meristem. First (up to 5 mm) to mid third (up to 20 mm) instars construct frass chains, on the tip of which they rest when not feeding. The study reported here was designed to provide data on larval behaviour and its relation to ant predation on the host plant, and to evaluate through ®eld experiments the ef®ciency of frass chains as refuges against walking predators.