Eastern Tent Caterpillar Egg Hatch Is Underway

Eastern tent caterpillar (ETC) eggs, which were laid last June, are hatching just as leaf buds are swelling on wild cherry trees.  Newly hatched eggs are easy to identify by the small holes that the tiny larvae chew as they make their exit.  The small caterpillars will stay near their egg mass for a short time before moving to feed on expanding leaves.  Eggs will continue to hatch through early April; caterpillars will be active for the next 4 to 5 weeks.

Figure 1. Eastern tent caterpillar egg mass on wild cherry twig.

Figure 1. Eastern tent caterpillar egg mass on wild cherry twig.

ETC grow and develop as long as the temperature is above 37°F; the warmer it is, the faster they will grow.  Cold temperatures will slow them down, but the tent and a general cold hardiness of the species will keep them from being affected drastically, even if temperatures drop below freezing at night.

ETC populations in the region appear to have been gradually increasing over the past few years, which can happen with many insects.  It is too early to tell what the 2016 level will be, but it is normal for insects to be very abundant in some parts of a county and at moderate to low levels in others. In about 2 weeks, ETC tents should be about the size of baseballs and easy to spot in trees. If control measures are needed to reduce ETC numbers, steps should be taken before caterpillars leave their trees.


By Lee Townsend, Extension Entomologist


Posted in Forest Trees, Landscape Trees & Shrubs