As the seasons move toward autumn, fall webworms are becoming more visible in the local trees and shrubs. They seem to be everywhere. They’re in many different species of tree including redbud, elm, mulberry, ash, and maple to name a few. They don’t seem particular about what type of tree leaf they eat. One resource has them listed as consuming the leaves of 400 species of woody plant (trees and shrubs).
The small moth larvae’s silken webs cover the leaves as the caterpillars consume them, safe inside the web. The caterpillar’s main predators, birds and wasps, have a difficult time getting at the larvae within the multi-layered web.
Wasp species, such as yellowjackets and paper wasps, are at the height of their season. Their nests, or hives, are going full-bore. Females from the hives spread out across the landscape in search of meat sources to feed the larvae back at the hive. The meat they seek is often caterpillar flesh. The small webworm caterpillars are just the right size to be placed into the hive’s brood cells to feed the larvae.
The webs constructed by webworms are formidable barriers to the wasps, who can see the caterpillars within but can’t seem to get at them. Occasionally they break through the silk but soon find that there are layers upon layers of silk. It becomes a battle for survival, a major effort to just get back out of the web again. Sometimes they struggle in vain. Often, though, they manage to free themselves, although empty-handed, without the reward of a caterpillar for all of their labor.
There are many points, barb-like projections and angles on a wasp’s body and legs. The more they struggle the more tangled they become.
Wasps must posses a memory for such things. I don’t find many dead wasps within webworm tents, or webs. Once they free themselves from a webworm web, they probably don’t attempt to raid another. However, while briefly standing in front of the web pictured, three different wasps landed on and explored the web. Were these uninitiated wasps, wasp that had never been trapped within a web?