Yesterday I found young eastern tent caterpillars building a tent. They seem a little late this year but we’ve had a cool spring. Last year by April 10 I saw large tents full of caterpillars. The young caterpillar above does not have the characteristic colors and pattern of more mature caterpillars.
You have probably noticed eastern tent caterpillars infest the same trees year after year. This is probably because the caterpillars pupate in protected areas, like wood piles or under bark, near the tree where they hatched. They prefer cherry and apple trees so when the female moths emerge in early summer they find the same trees.
The moths lay a couple hundred eggs in early summer on thin branches.
The egg masses look like dried foam. When trees don’t have leaves you can often look up and see them on the branches. If you prune off the egg masses in fall or winter you won’t have caterpillars the next spring.
Eastern tent caterpillars can defoliate large areas of a tree canopy. However, this usually does not cause long term harm. In some cases the crotch of trees, where nests were, can become darkened or slightly rough or disfigured. Prune or poke the nests to remove or disrupt them. More management information is here. Some relatively new insecticides for caterpillars include XXpire, Provaunt, and Acelepryn.