What are those silvery webs in the trees?

Small Tent Caterpillar web in the crotch of a plum tree in early spring.

Small Tent Caterpillar web in the crotch of a plum tree in early spring.

Have you noticed silvery webs in the branches of the trees this year? Or perhaps you noticed the presences of lots of caterpillars crawling on the ground and across parking lots? This year the Tent Caterpillars are coming on full force.

Even before the leaves were on the trees this spring, I noticed small tents with tiny little caterpillars. They were about 1/2″ long when were were on our Spring Break backpacking trip. I’ve been watching them progress and this week I noticed they’re about 2 1/2″ long and they’ve left the tree and are marching onward in search of food.

Picture of tent caterpillar crawling on a branch in sunlight in spring.

Tent Caterpillars are actually rather attractive individuals.

The newly hatched caterpillars form a tent-shaped web shelter in the crotch of the host tree. They crawl along the tree, often a wild plum or black cherry, and eat the newly emerging leaves. They return to the web for shelter. In fact, the tent has multiple layers which create separate compartments that the caterpillars use to regulate temperature. This allows them to use the sun’s warmth to extend the season, essentially creating their own greenhouse.

Eastern Tent Caterpillar web in the crotch of an old plum tree.

Web of the Eastern Tent Caterpillar in the crotch of an old wild plum tree in Piney Creek Wilderness.

The best feature of tent caterpillars, though, is the gross factor. They mass together in their tent, writing over each other. It’s a sight sure to make any pre-teen girl squeal with disgust. It’s pretty cool to watch, though.

Writhing mass of Eastern Tent Caterpillars, Malacosoma americanum, on a branch of an old plum tree.

Writhing, wriggling, mass of Tent Caterpillars in the early morning sun.

What do you think?

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