Spongy Moth

What is a Spongy Moth?

(Lymantria dispar)

Spongy Moth (formerly known as ‘Gypsy Moth’) is an invasive pest introduced into the US over 150 years ago. It feeds on a wide range of tree and plant species, but prefers oak foliage.  Spongy moth causes major defoliation in Vermont’s forest, rural and urban settings in periodic cycles that are often preceded by prolonged drought conditions. You may go years without seeing one, and then have an outbreak. Healthy trees can generally survive several years of defoliation; however, repeated defoliation can cause significant decline in tree health and, in some cases, tree death.

What to look for – Signs & symptoms

Spongy Moth infestation can be pretty easy to spot. Here are some things to look for in your trees and around your yard:

• Egg Masses: covered with buff or yellowish hair from the female and averages about 1-1/2 inches long and about 3/4 of an inch wide. Moths will lay egg masses on just about any surface, including trees, household furniture, and other things around your yard.

• Caterpillars: newly hatched caterpillars are black and hairy and quite small. Later stages have a mottled yellow to gray pattern with tufts of bristle-like hairs and a distinctive color pattern of five pairs of blue dots followed by six pairs of red dots along their backs. 
• Adult Moths: male moths are brown with a darker brown pattern on their wings. Females are slightly larger, with a two-inch wingspan, and nearly white with dark saw-toothed patterns on their wings. Male spongy moths can fly but female spongy moths cannot. 
• Defoliated Trees: Caterpillars crawl into the canopies to munch on tree leaves. If populations are high enough, they can strip the tree of its leaves. This can put stress on the tree. Defoliation is serious but not necessarily the end for affected trees. Factors that must be considered are the number of larvae, and whether this is a repeated defoliation from a prior year.

How does Teacher’s Tree Service manage Spongy Moth?

• Maintaining and Improving Tree Vigor:  Keep your tree appropriately watered and ensure it has the nutrients it needs to thrive. Teacher’s offers a custom blend of balanced macronutrients with biochar and humic acid injected directly into the root zone to maintain the overall health and wellness of your trees.

• Regular Pruning:  Part of maintaining your tree’s health is a regular pruning. Teacher’s Tree Service has all the tools and experience to help you keep your tree in tip top health.

• Insecticide Treatments:  If your tree is already infested or is located in an area where Spongy Moth populations are rising, treatment may be necessary to ensure the recovery and longevity of your tree.  Insecticide treatment options include trunk injections, soil injections, or, for smaller trees and fruit trees, a BTK foliar spray. Timing of treatments is critical; please contact us as soon as you notice that your tree is stressed, or when you see higher numbers of Spongy Moth in your neighborhood.