Environment DEC
From the June 2007 issue
Watch Out for Spring Caterpillar Pests
Read how to respond when you find your trees infested with tent caterpillars
New York State Department of Environmental Conservation (DEC) reminds people to be on the lookout for common spring insect defoliators. DEC also provides guidance on how to control these pests.
Caterpillar Populations Projected to be High
"Populations of forest tent, eastern tent, gypsy moth, and saddle prominent caterpillars, and the group of caterpillars commonly called inch-worms are projected to be high again this year," DEC Commissioner Grannis said."Most trees will survive an initial defoliation by caterpillars in the early growing season and usually re-foliate in early summer when they are gone. But defoliation can weaken trees making them more susceptible to other potential stressors such as drought, disease or other insects, so consecutive years of defoliation can kill a tree." Fall surveys conducted by the DEC Forest Health crews have shown that large populations of these defoliators exist in several counties, most of which had caterpillar problems last year. Because these caterpillars are somewhat mobile, damage can easily spread to other counties.
Mechanical vs. Chemical Treatment
Effective mechanical treatment options for controlling infestation on individual trees include hand removal of egg masses, inhabited caterpillar tents and pupa, and installation of sticky tree wraps on trunks to capture caterpillars as they move up and down trees. If you choose to use pesticides to control infestations, they should be used wisely and according to label instructions. DEC recommends using a New York State registered pesticide business that employs certified pesticide applicators. Some pesticides used to control harmful insects are contact poisons and could endanger a variety of beneficial insects, such as honeybees, as well as nesting birds and other animals. Spraying is not effective against pupae or egg masses, and is less effective once caterpillars reach one-inch in length. To find a list of registered businesses that can perform pesticide applications, visit the Pesticides web page on DEC's website.
Whether mechanical or chemical, treatments are most effective when applied while caterpillars less than an inch long. Generally, treatments are less effective when leaf-loss is noticeable. Do not attempt to burn caterpillars and their tents while they are on trees. This is hazardous to the health of the tree and can be very dangerous. Contact your regional DEC office or county Cornell Cooperative Extension office (see "Related Off-site Links" below) for additional information and management options.
More Information
For more details regarding pests that defoliate trees in spring, including areas that can be affected, visit the Insects & Other Species web page on DEC's website.
