Forest tent caterpillars hatch in early spring (March) and may reach large numbers. This fuzzy blue caterpillar with small silver keyhole spots down its back feeds primarily on sweet gum, birch, cherry, elm, willow and oak leaves. These caterpillars do not sting or bite and are more of a nuisance than anything. The damage to the leaves is usually aesthetic and will seldom kill the deciduous host. The caterpillar may feed other tree and shrub leaves. The caterpillars spin silken threads and may be seen hanging down from trees by these threads in the wind.
The female moth lays eggs on the branches of host trees in a mass of several hundred eggs. The caterpillar overwinters in the egg stage. Once the eggs hatch, the life span is complete in 5 to 6 weeks with the larva (caterpillar) spinning a cocoon. The moth emerges from the cocoon in about 10 days and will live about five days. During this time the egg masses are laid. We have only one generation a year.
Most years these caterpillars do not need to be controlled with an application of an insecticide. If you wish to spray an insecticide, several insecticides may be used including Orthene TTO, carbaryl (Sevin), malathion, Bacillus thuringiensis (a biological) and Cyfluthrin (Bayer Advanced, Multi-Insect Killer). Always check the front of the label to make sure you are purchasing the correct active ingredient. Make sure to follow the mixing instructions and precautions on the label. Do not allow children and pets to enter the sprayed areas until the sprayed surfaces have dried. Children and pets may have increased exposure to the insecticides since children may put sprayed objects in their mouth or fingers that have touched sprayed surfaces. Pets lick their paws and fur that may have come in contact with insecticide residue.
If you want additional information on this insect, come by the Extension Office in the Franklin Parish Courthouse for publications, go online to the LSU AgCenter web page at www.lsuagcenter.com or call our office at (318) 435-7551.
The LSU AgCenter and the LSU College of Agriculture