In the caterpillar world, hairiness is a means of passive defense. Most birds really don’t like to eat hairy things and for good reason. Some larval moths develop stiff irritating hairs that shed and stick like miniature barbs while others adopt the “birds will not eat a pom-pom” approach by covering themselves with long silky locks that clog up throats. The avian aversion to hair is understandable. I don’t like to eat hairy things either – extremely fuzzy peaches, for instance, are a challenge and I would never eat a whole cat. In some parts of the world where people actually eat caterpillars, they gravitate to the hairless ones such as African Mopane worms. (By the way, for those of you now forming some sort of statement pointing out that insects and peaches don’t have real hair, I wish you to stop right now. I know this and I don’t care this).
Fall webworms are a fuzzy lot, so you’d think that would be enough in itself for a short happy life. These larvae are covered with fine white silky hairs and they eventually become fuzzy white moths. That’s enough mouth-gagging pile to stop any mouth. They collectively know, however, that there are many other agents of death out there that have no aversion to hair such as parasitic wasps and ‘piller pillaging hornets. (For those of you who are now preparing to say that insects don’t really think, I would again ask you to stuff a pom-pom into your mouth). Webworms take the predator defense thing one step further by living in huge colonies surrounded by silken walls. In other words they survive by being a hair ball within a hair house – a furball protected by a firewall of fuzz – a mffffa muffash …(hey, who stuffed ‘tha cat in my mouf!).
Webworm colonies are easy to spot and to contemplate. Their large silken colonies begin to appear in mid-summer and become more obvious as the season progresses into fall (thus the name). The tactic employed by these creatures, from the time they emerge, is to collectively wrap a cluster of leaves in silk and collectively eat those leaves. There can be as many as 500 individuals in group. As the members of the colony grow in size so too does their required dwelling space. They take up to six weeks to mature, so large clumps of leaves eventually become encased and stripped.
The singular caterpillars never leave the confines of their silken haven until they are just about ready to grow up (they fend on their own during their last instar just before pupating). Therefore they have to live with the consequences of such cloistered living. Their old shed skins and piles of poo (see detail below) accumulate inside the web matrix and make for some pretty untidy house conditions. It’s o.k. for these kids to live in squalor as long as they are safe. Unfortunately, they are not completely shielded against the world. When a rip occurs, wasps and other small predators can still have their way with the web dwellers.
You also may have noticed earlier that I said MOST birds are adverse to hairiness. There are a few who delight in such treats as long as they can find rips in the colony fabric. There is one instance in which a yellow Warbler was seen literally emptying a colony of it’s residents. Yellow-billed Cuckoos also delight in such fare. I have seen them joyfully, and repeatedly, smack small hairy caterpillars against limbs to pulverize them before eating. I guess that is the trick to eating hairy things. In the case of Fall Webworms, one early naturalist recorded 325 of the dead larvae in the stomach of a single cuckoo. Now, that’s a hair ball! That bird was cuckoo for …mmfho… hey, who stuffed that Pomeranian in my mouf!
To wrap up this discussion, it is necessary to say that webworms are not major tree pests. In spite of their dramatic flare for tent-building and leaf skeletonizing they do not generally cause any lasting harm. Although they seem to have a special liking for Black Walnuts in these parts, they are known to feed on around 90 species of deciduous trees. This is probably one of the largest menus known among the caterpillar world. The rest of the world may be picky about eating them, but they apparently are not picky about what they eat. Or, should I say that they are hairy liberals when it comes to tree food – fuzzmapolitans who mmph…momph…. Hey, you know, these things don’t too taste bad.