Trees can usually survive such defoliation, but with reduced growth. Disease, other insects, nutrition, moisture and general poor condition may cause tree mortality in defoliated trees. Higher defoliating populations of forest tent caterpillars typically drop after two years due to natural conditions and diseases. Freezing weather shortly after eggs hatch kills large numbers of caterpillars, and excessively high temperatures later in the spring kills large numbers of adults and reduces the viability of newly laid eggs. Egg masses on branches of small trees around the home can be removed and destroyed before hatching.
All controls are most effective when applied as soon as all eggs have hatched.
As the caterpillars grow they become more difficult to kill. Where trade names are used, no discrimination is intended and no endorsement by Cooperative Extension is implied.