Tent worms have hearty appetites, so if you have an infestation, it is likely that your precious oaks, aspens, and cherry trees are in grave danger. Tent worms will nosh and nosh until there’s nothing left, so prevention is the key. The first thing to consider when devising a prevention plan is to determine which type of tent worm (caterpillar) is on the way. There are three different types of tent worms including the forest tent caterpillar, the eastern tent caterpillar, and the gypsy moth caterpillar.
The yellow marked forest tent caterpillar can be spotted spinning its silk mat on the leaves of oaks, aspen, sugar maples, and other types of trees. An invasion of these hairy, dark-colored caterpillars can last from two to three years, and they occur in intervals at eight and 10 years. The eastern tent caterpillar will avoid your oak trees, but it will devour crab, apple, and cherry trees. You are more likely to see hundreds of eastern tent caterpillar webs in trees when there is an infestation, than if there is a forest tent caterpillar invasion. The eastern tent caterpillar is also quite easy to spot. At two inches long with a black body with a yellow stripe, this worm is a standout among all others.
The gypsy moth caterpillar will eat just about anything. It will feast on more than 300 different types of shrubs and trees, but it does have a few favorites. The gypsy moth caterpillar has a strong attraction to ash, birch, apple, crab apple, and wild cherry. Although annoying and destructive, the gypsy moth is quite the sight. These hairy worms have striking red wisps along the body.
Unique and beautiful as these creatures are, they are a pest for farmers, gardeners, and landscapers. They defoliate trees and in some cases, these tiny creatures can kill even the grandest of trees. To get rid of them (entirely), chemical controls are needed. To get rid of many of them, you can remove the branches they are living on. Other options include removing the worms by hand and using a stick or other object to take off the tent like structure. A bucket of soap and water placed under the tree might help, but this will only trap and kill any worms that might fall from the tree.
The best chemical control is Bacillus Thuringiensis (BT). BT is a bacterium that kills pests, but it won’t harm your plants. You can purchase BT at most plant stores, hardware stores, and garden centers. Sprays made of insecticidal soap may be effective as well. The best time to spray is in the morning when the caterpillars are out “sunning.”
Early detection is the best preventative method. Inspect your plants and trees daily to check for signs of eggs and worms. The eggs are black and they can be found on branches. You can try crushing them or as stated earlier, you can remove the branches or spray. Anything inside of the eggs will die, but if the worm is already an adult, insecticidal soaps may only make them sick. BT is the best bet to combat the stronger adults. You should inspect branches during the late winter months. If you find any egg cases, spray like crazy! Good luck.