 When you're out in the woods for a nice weekend, you oftentimes bring along a tent for protection against the elements. These caterpillars are doing the same thing. There are many species of tent caterpillars and some other types of insects that also produce tents. The most common and damaging in Wyoming is the western tent caterpillar, which can be seen in May and June. If you've seen tent producing caterpillars in the fall, it is most likely the fall webworm. Tent caterpillars rarely cause plant damage other than some defoliation. The western tent caterpillar is the most destructive and sometimes produces a widespread outbreak, which at its highest level can kill stands of aspen. Caterpillars lay their eggs on stems which overwinter. In the spring, they emerge as caterpillars. The caterpillars construct a silk intent for shelter where they rest during the day and venture out to feed mostly at night. They expand the tent as they grow. When they are fully grown, they leave the tent and spend a silk cocoon where they pupate into moths. They only have one life cycle per year. Tent caterpillars serve as a food source for birds, predacious bugs, hunting wasps, and many other animals. Although a nuisance in the backyard, tent caterpillars rarely reach high populations in our western forests. From the University of Wyoming Extension, I'm Mae Smith, Exploring the Nature of Wyoming.