Look for the conspicuous white masses in the forks of tree limbs in early spring -- these are the webs or tents of the eastern tent caterpillar.
A colony of hairy caterpillars lives in the tent, coming out to feed at night. Trees most commonly affected are wild cherry and plums, and fruit trees, such as apple, cherry, flowering crab apple, plum and chokecherry. It is related to the eastern tent caterpillar, which every seven years defoliates forests of poplar, birch and oaks.
While the eastern can defoliate all of a tree, it rarely kills the tree, it is mainly cosmetic. Control includes removing and destroying eggs masses in winter, removing the small tents by hand or larger webs with a broom or stick, and then burning or bagging for disposal. For caterpillars less than one inch in length, use the organic products horticultural oils, insecticidal soaps, or Bacillus thuringiensis var kurstaki.
The best time to apply these is when it is warm and the caterpillars are out and actively feeding.
Do not use insecticides that can kill bees, if the tree is flowering. More information may be found from the UW Extension publications Web site Iearnincistore.uwex.edu.
