SILKWORM CATTERPILLAR (Arsenura batesii) ©ggallice
Saturniid caterpillars are large (2-4”/50 to 100 mm in the final instar), stout and cylindrical. Most have tubercules that are often also spiny or hairy. Many are cryptic in coloration, with countershading or disruptive coloration to reduce detection, but some are more colourful. Some have stinging hairs.
A few species have been noted to produce defensive clicking sounds with the larval mandibles when disturbed (e.g. Saturniini like Actias luna and Polyphemus Moth, Antheraea polyphemus). Most are solitary feeders, but some are gregarious. The Hemileucinae are gregarious when young and have stinging hairs, those of Lonomia containing a poison which may kill a human.
Some saturniids produce more than one brood a year. Spring and summer broods hatch in a matter of weeks; autumn broods enter a state known as diapause and emerge the following spring. How the pupae know when to hatch early or hibernate is not yet fully understood, though research suggests that day length during the larvae’s 5th instar plays a major role. Longer days may prompt pupae to develop early, while shorter days result in pupal diapause.
Fact Source: http://en.wikipedia.org/wiki/Saturniidae
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