Western Tent Caterpillar Update

Management:

NEVER use fire as a control method for tent caterpillars (or any other pest problem). Burning the tents can result in more damage to the tree. Additionally, this practice may result in personal injury and property damage. In 2003, several media's recommended the use flame weeders or small torches for ridding of tents. Fire should never be used as a pest control practice. Fire is unpredictable and dangerous.

A simpler solution is found in pruning off the tented branch. It is best to do this at night or early morning, when the caterpillars are congregated in the tent. Dispose of the branch by placing into a yard bag or trashcan so the larvae cannot escape and continue feeding. Other mechanical control methods can be implemented to manage the egg stage. Egg masses are easily seen on small trees and will simply peel off from the bark. You can do this in fall and winter.

Weather and temperature are important natural regulators of tent caterpillars. Many animals will also regulate these caterpillars such as birds, parasitic wasps and flies, and diseases (virus and bacteria). Conserve these good guys by reducing broad-spectrum insecticides and non-target applications of insecticides. Learn more by continuing to "Biological Control."

Chemical management of tent caterpillars is an extreme response to a serious tent caterpillar problem. Most times, mechanical controls are effective. When young trees are heavily infested, the use of insecticides may be warranted. If a biological insecticide is used such as Bt (Bacillus thuringiensis ), be sure to spray the entire foliage that is being affected. Caterpillars must eat a good amount of the treated foliage to be sickened. Bt is most effective for managing small, young larvae in the spring. If a contact insecticide is used, treat the larvae that congregated in the early morning. This way, you do not have to spray the entire tree, just the tents. In doing this, be sure that your pesticide is penetrating the tent. Making tears into the tents may be worthwhile before you spray. As the caterpillars mature, it is important that the surrounding foliage is also treated; the caterpillars disperse from the tent as food becomes scarce. As with all our chemical recommendations, be sure to read and follow the label. Be sure to distinguish label directions for fruiting, edible trees and ornamental trees. Visit WSU Hortsense (http://pep.wsu.edu/hortsense/) for current recommendations.