In the last week the Arborist at Dallas Tree Surgeons are seeing Tent Caterpillars all over the DFW metroplex. Just this morning I had two friends call me and ask, “What are these worms on my tree?” We are expecting this to be common question this year.
Tent Caterpillars are social caterpillars that mass on trees after they hatch in the spring. They are known to live on and eat Oaks, Elm, and Cottonwoods. They are often confused with Web Worms, but unlike the Web Worm they make their webs on the trunks of the tree and not in the canopy. There are many species of Tent Caterpillars the four most common are Eastern, Forrest, Western, and Sonoran. The ones we are seeing all over East Dallas are Forrest species. They all are hairy and are colorful. They do not sting and are not harmful. They can be bothersome since they travel from the tree crawling on homes, outdoor furniture, and cars. When the caterpillars mature they permanently leave the tree and make their cocoons in dark places near by. They emerge as small brown moths. Click here for detailed information.
Tent Caterpillar Damage to Trees
Tent Caterpillars eat the leaves of the trees they infest. They do not usually cause lasting damage because they do not usually completely defoliate trees. Since they feed early in the spring the leaves often regrow.
However, if the tree has a very heavy infestation, more than 25% of the canopy has been defoliated, the tree is already stressed or the tree is very young it may be necessary to treat them.
Tent Caterpillar Treatment
If a tree is stressed by preexisting conditions or a large percent of the canopy has been eaten by caterpillars then our arborists recommend using high quality, biologically based soil-conditioners and natural, organic fertilizers that optimize the growth and health of your trees increase the overall health of the tree. If the caterpillars are still active they can be mechanically removed by spraying or scraping them away, the infested branch can be pruned, or they can be treated chemically.