Gardening Tips: Controlling Eastern Tent Caterpillars

Gardening Tips: Controlling Eastern Tent Caterpillars I met someone this past week who told me that he looked forward to my articles each week to see what new pest or critter I can think of to write about. Well, I am back again this week with another just like I promised him. This time it is something that most of you have seen before, even if you don’t know exactly what it is or what to do about it. I’m talking about Eastern tent caterpillars. You’ll see Eastern tent caterpillars this time of year on mainly cherry, apple, and crabapple trees, as well as some others. The caterpillars emerge from eggs laid the previous year, and spin a silk webbing in the crotches of tree branches (where the branch meets the trunk, or a small branch meets a larger one). As the caterpillars grow, they will continue to spin the silk webbing around their tent-like nest, expanding it in size. The caterpillars will leave the nest several times a day to look for food on days when the weather is nice, but will return to the nest at night. After about six weeks, the caterpillars leave the nest and will spin individual cocoons on nearby trees, fence posts, or buildings. They will emerge from the cocoons as moths in early summer and will eventually lay eggs. Caterpillars will emerge from these eggs the following spring, repeating the life cycle. How does this affect your trees? The main effect will be the unpleasant sight of the caterpillar tents in the trees. The caterpillars will feed on leaves of the trees, but generally will not damage the overall health of the tree unless there are a large number of tents on a single tree, or if the tree is infested repeatedly year after year. Therefore, how you control the problem is dependent on how many caterpillar tents are present and the amount of damage you are willing to tolerate. Usually, if there are just 1 or 2 tents per tree, you can simply take a stick and remove the tents from the tree, and then stomp the caterpillars out on the driveway. Do not try to burn the tents as this can cause damage to the trees. If the problem is more severe, or if the tents are too high to reach with a stick, you can spray the tents with Sevin (carbaryl), Orthene (acephate), or Talstar (bifenthrin). It may be difficult to spray branches higher up in the tree, so use caution when spraying, do not spray when it is windy, and always follow the directions on the product label. Eastern tent caterpillars are a spring time pest but are similar to fall webworms, which appear between July and September, and tend to infest pecan, persimmon, mimosa and sourwood trees. In addition to appearing later in the year, fall webworms also differ from the Eastern tent caterpillar in that they tend to form their webs at the tips of branches, rather then where the branch meets the trunk. Therefore they tend to be higher up in the tree and more difficult to reach and control. If you have had problems with fall webworms in the past on certain trees, you may want to consider spraying the trunk of the tree, the lower limbs, and soil around the base of the tree with Sevin, Orthene, or BT (Bacillus thuringiensis) in June or July before the webworms emerge. Generally, the webworms will lay eggs in older leaves and branches that have fallen to the ground, and the larvae that emerge from the eggs will crawl back into the tree after they hatch. Raking up and disposing of any old leaves and twigs around the base of the tree is always a good idea as well. The Halifax Farmers Market will be open Wednesday April 19th from 8 AM to 5 PM. There will be strawberries, baked goods, Avon products, live plants, hanging baskets and crafts available. Matthew Stevens is the horticulture extension agent for Halifax County Cooperative Extension. If you have any questions about this article or other aspects of your home gardening, please contact Matthew at 583-5161 or [email protected].