From my observations and from information received from Pennsylvania Bureau of Forestry, Forest Pest Specialists, the population of Forest Tent Caterpillar (FTC) appears to be on the rise in parts of the northern tier of Pennsylvania. These caterpillars are native insects that periodically reach high populations. They can defoliate an entire tree in a very short period of time. They are particularly fond of maple and aspen. They will also feed on a wide variety of other hardwood species. The eggs hatch in the spring about the time of leaf expansion. They tend to hang together in colonies and congregate during rest periods. They do not spin the large tents as do their relatives, the Eastern Tent Caterpillar. Five to six weeks after hatching they spin whitish-colored cocoons in bark crevices or rolled leaves. They emerge as buff-colored moths in about ten days. They mate and then the female lays eggs. The egg masses are dark and generally encircle a twig. The eggs overwinter and hatch again in the spring.
A very important parasite of this caterpillar is a large, gray fly. The populations of this fly can be very large during forest tent caterpillar outbreaks. They do not bite or sting people but they can be very annoying since they do like to land on people and regurgitate on buildings and hung-out laundry. The good thing about these flies is that they are a major factor in the natural control of FTC.
At this point in the life cycle of forest tent caterpillar, the adult females are laying or have already laid their eggs. It probably wouldn’t hurt to check out your trees, if you had some forest tent caterpillar, and look for egg masses in a few weeks. This can give you an idea if you may be dealing with this insect next spring. For more information go the Bradford County Extension website, click on the natural resources link and then the forestry resources link. Scroll down to the photo of the forest tent caterpillar and click there.
