We think of moths and butterflies as relatively harmless creatures, but there are certain species with a darker side—for example, carnivorous caterpillars that eat aphids, butterflies that drink alligator tears, or "vampire" moths that feed on livestock blood. Add to that list the newly discovered "bone collector" caterpillar, which conducts daring raids on spider webs for sustenance, camouflaging itself in the body parts of already-consumed insects to avoid being eaten. Not only that, but according to a new paper published in the journal Science, the caterpillars can tailor those insect parts, nibbling away at any excess material to ensure a proper fit.
Daniel Rubinoff, an entomologist at the University of Hawaii, Manoa, studies a genus of moths found in Hawaii called Hyposcoma, or as he has dubbed their larval form, "Hawaiian Fancy Case" caterpillars, so named because they spin their own casings, adding to them as they grow, although the materials used can vary widely. There are now more than 600 species within this genus, many of them not yet officially described, so it was a rich research area to explore.
The discovery of the bone collector species was serendipitous. "You never forget your first bone collector," Rubinoff told Ars. His team was on Oa'hu looking for Hyposcoma when they came across a little tree hollow and spotted something at the bottom that at first glance just looked like "a bag of bug bits." The caterpillar then stuck its head out, and the researchers realized it was a new kind of case. Rubinoff assumed that the spider web also found in the tree hollow was a coincidence; the caterpillar just used the materials readily available in the tree hollow to make its fancy case.
