How to Identify Eastern and Forest Tent Caterpillars
Tent caterpillars aren’t the end of the world. They may attack your ornamental or orchard trees but unless a tree is already suffering from other stresses it should recover quickly.
These native, spring ephemeral caterpillars are often confused with fall webworms (Hyphantria cunea) or gypsy moths (Lymantria dispar). Fall webworms also have a brief life cycle (in the fall instead of the spring) and cause minimal damage to their host trees. Gypsy moths are an invasive species that can breed all season and destroy the plants they eat.
Shortly after hatching from the previous season’s eggs, eastern tent caterpillars begin building silk nests which they enlarge over their short feeding season. Their preferred host trees are wild cherries but they will also eat other species in the apple (Malus) and cherry (Prunus) families.
Most of the time the caterpillars do little damage, even if they completely defoliate the tree. Once their life cycle is completed the tree simply puts out new leaves and moves on.
Forest tent caterpillars do not build an enclosed nest like their eastern relatives. Instead, they huddle together on silk pads spun on the bark of their favorite trees. They also eat a broader range of species than the eastern tent caterpillar but in the Appalachians this is usually some sort of oak.
Forest tent caterpillars are more likely to be spotted singly or on the trunks of trees while you are hiking.
Both of these tent caterpillar species are furry and harmless to touch. They make great educational pets if you have their host plant nearby so that you can replenish their food supply. A well-ventilated container (cleaned frequently) makes an excellent caterpillar home. Crowded or dirty cages are prone to an insect disease called grasserie. All caterpillars are voracious eaters and if they are allowed to run out of food they may pupate early as an “emergency.” This usually results in a smaller-sized butterfly or moth (though sometimes they will die).
Tent caterpillars turn into somewhat plain, clumsy brown moths. Their adult photos can be seen here: