Having set the bands two weeks earlier this year, I have been able to see a number of species that I only rarely encountered or did not see at all last June. The most striking and impressive of these have been the numerous Ilia Underwings (Catocala ilia) that rest so cryptically on the bark. Last year, I started work at the tail end of this early species’ active period and so only caught 1. This year however, I’ve already seen around 10 very large individuals.
Moths of the genus Catocala are commonly referred to as underwings because of their startling orange hindwing coloration. This flashy patterning is used to scare and confuse potential predators that disturb the otherwise cryptic moths. At rest, they disappear against the bark and leaf little owing to the earthy gray, brown, and black patterns of their forewings. When disturbed by a potential predator, a startling flash of the hindwings sends them running or at least creates enough confusion for a quick getaway.
Interestingly, this startling defensive behavior is not limited to the adult moths. Many underwing caterpillars, Catocala ilia included, are extremely cryptic at rest (see below), but when disturbed they will show off their bright, flashy undersides in a thrashing, writhing display (see video in next post).
Catocala ilia resting on a white oak. Can you spot it?
A classic gray bark-like Catocala ilia.
A distinct lichen form of Catocala ilia.
The characteristic pink venter of Catocala ilia.
Seeing all these Catocala and other species, just shows again how effective this simple collection technique is. If you’re interesting in caterpillars or just a nature lover, then I recommend you set up a burlap band in your yard or wooded area. It is the easiest way to encounter a diversity of caterpillars and other insects, many of which would be impossible to find otherwise.
Oak Hairstreak Study 