Caterpillars have a variety of defenses other than stinging hairs and toxic flesh. They tend to be active at night and group together in daytime under protective webs. When I touched the leaf on which the young hickory tussock moths were sitting, a surprising thing happened- numbers of caterpillars began to drop down to the ground quickly on web lines (see photo). You might wonder why this would be necessary when these caterpillars seem to be so well protected. However virtually all good defenses have spawned a specialized predator that can circumvent the defensive strategy- in this case it is the yellow-billed cuckoo (see photo) which is a fuzzy caterpillar eater. Not coincidentally we have noticed far more cuckoos on our property this year than last when caterpillars were not so numerous. So the hickory tussock moth caterpillars drop from the tree at the slightest indication of a cuckoo being present, and can then crawl back into the tree after the cuckoo leaves.
The intricate natural history of something so seemingly inconsequential as a tiger moth caterpillar tells us once again that the adaptations of this larval moth are subject to very specific design criteria to maximize its chances of survival and subsequent reproduction. So even if we destroy some of these creatures that eat our yard plants, we cannot fail to marvel at their remarkable methods of existence.
Galax, VA & Englewood, FL