Tent Caterpillar – They Are Back!

While many want to blame the gypsy moth, the hard, protective shell. The eggs overwinter and most recent leaf feeding caterpillar that has taken hatch out as tiny larvae in early spring usually much of northern Michigan by storm is really the early to mid April. If you have potential tree Eastern Tent Caterpillar. If it makes a tent silk hosts, careful observation and hand control may nest in the branches of trees then it is the tent be all you need. In fall, winter, and early spring caterpillar, not the gypsy moth. look for egg masses and cut or scrape them off and either burn or soak them in soapy water. In The good news is the tent caterpillar is not as early spring, tear out nests by hand or with a damaging to trees and not as annoying to humans garden tool and destroy the young caterpillars. as the gypsy moth. But the bad news is this is a This can be easily accomplished by dropping the large invasion of the tent caterpillars. Like all nest parts and caterpillars in a pail or dishpan of insects their populations grow in size for a few soapy water. People often burn the nest out of the years and then crash and seem to disappear for trees, but this method is not recommended five years or more. 2008 is seeing higher because of the safety hazard. populations of tent caterpillars than what we have seen in the last fifteen years so they will still be There are several natural enemies of the tent noticeable and at least a little annoying for a few caterpillar. A parasitic fly attacks full grown more weeks. caterpillars. The fly looks like a housefly, but is twice as large, has a light gray thorax with three Eastern tent caterpillars generally attack black stripes. The fly’ maggot consume the understory trees, particularly crabapple, wild caterpillar internally and kill it as a pup (cocoon). cherry, and apple, but also will feed on peach, Ground beetles and predaceous wasps also eat pear, plum, rose, hawthorn, and others. The tent caterpillars, as do various birds, most notably larvae often eat all the leaves off a tree. Although Northern orioles. this damage is unsightly and worrisome, it usually only weakens the tree after three or more To protect and help increase the population of years of more than 50% defoliation. beneficial insects, broad spectrum spraying of insecticides is not advised. Instead the best time They are a black, hairy caterpillar with white to spray the tent caterpillar is when they are still stripes with narrower brown and yellow line on concentrated in their nests in May. the sides and blue spots. When full grown, they are about two inches long. Caterpillars are the Insecticides with the chemical ingredients like only stage, which cause feeding damage. In early Acephate, carbaryl (Sevin), malathion, and B.t. June these grown caterpillars leave the tree and are the recommended insecticides. Bacillus crawl everywhere, seeking locations to make thuringiensis (B.t.) is the most environmentally cocoons. After about six weeks of feeding and sound organic control method but it must be growing in mid-June the caterpillars spin white or applied in May to be effective. If your trees have yellowish white cocoons, about one inch in been defoliated, water and fertilize them. One length. At this point as far as homeowners are inch of water, applied every one to two weeks is concerned they virtually disappear for the recommended if rainfall is not present. summer. By early July the tent caterpillar will be a distant Adults are reddish brown moths with stripes on memory that may not return in high numbers for the forewings and have a wingspan of 1" - 1 1/2". many years, most trees they feed on will leaf back They emerge in July. The adults mate and out and we will be able to worry about things like females lay about 200 eggs in a ring around gas prices again. twigs, lying on a foamy secretion which dries to a