Western tent caterpillars are hairy with orange and black markings. Adult moth is orangy brown. Forest tent caterpillars are hairy, light brown and have orange stripes. 

Tent Caterpillar-Ohio State University (left), Moth (megalopygidae)-Furman University (right)

Description
Adult moth are yellowy brown. Eastern tent caterpillars are brownish black and hairy as well. Adult moth is reddish-brown. All three caterpillars measure up to 5 cm long. The adult moth is 2.5cm-3.5cm wide.

Cocoon-Peers Online (left), Egg Mass-Ohio State University (right)

Habitat and Lifecycle
They are found everywhere in North America. They overwinter as eggs and hatch in early spring. They climb up tree trunks and build large silky tents around stems and leaves. They feed on surrounding leaves but return to their nests in the evenings. In the late summer look for their yellowy white cocoons attached to tree trunks. The adults hatch, mate and lay eggs that overwinter in the ground.

Webs-Ohio State University (left), Webs-Grassroots Lawncare (right)

Diet and Damage
The caterpillars are leaf eaters but they do not eat the leaf stems. They rarely kill trees but if there is severe infestation they can defoliate trees in no time and mature trees can take up to 2 years to recover. Luckily their nests are easy to see and therefore control is much easier at the first sighting of them. Their diet is usually fruit trees but they can be found in maples and many other hard and softwoods. Forest tent caterpillars don’t make ‘tents’ but rather form silky mats around nests. I’ve had yearly episodes of these guys in our hawthorne trees and apples.

Control
1) Bt
Applications of Bt sprayed daily will help prevent the pest from reproducing as they die quite quickly.
2) Hand Pick
In the evening when the caterpillars have returned to their nests you can clip off the branch with the tent and drop it in your fire pit. If the nests are too high you can throw rocks making holes in the tents and the birds will gladly eat them.
3) Hand Pick Egg Masses
Egg masses are black/brown and easy to see. The masses encase a twig. Cut the twigs and burn them.
4) Predators/Beneficials
Birds, chickens in your orchards, and parasitic wasps.