These caterpillars are named for the web like tent-shaped shelters they create at the branches of trees. The larvae feed on the foliage of fruit trees including cherry, apple, plum, chokeberry, and others. Extensive defoliation can result. Younger trees may not withstand the damage though mature and healthy trees are not affected too badly.
Symptoms: Characteristic tent-like webbing at the forks in the branched of the trees where the caterpillars return when dark or during rain will be present. Significant defoliation may also be seen. The caterpillars are two inches long when fully grown and have blue back and orange markings as well a white stripe down their back.
More information: University of Minnesota Extension
Photo: David Paulson & southcarolinapublicradio.org