Moths in Pennsylvania on Ash Trees

Gypsy Moth

• The gypsy moth (Lymantria dispar) is a frequent inhabitant of ash trees. Penn State University's College of Agricultural Sciences describes it as the most important pest of forest and shade trees in the eastern U.S. Adult male gypsy moths are dark-colored and able to fly while female moths are a mixture of white and black and do not take to the air. The larval stage of the moth -- a caterpillar -- feeds on the tree, often defoliating it.

Gypsy Damage

• The defoliation the gypsy moth produces on an ash tree in Pennsylvania is less damaging than the secondary injury it causes; a weakening of the tree that makes it more susceptible to injury from other insects and diseases. Shoestring root rot and attack by the two-lined chestnut borer are often fatal to an ash once the gypsy moth has fed on it. A number of natural predators typically keep the moth under control in the state.

Native Ash Borers

• The banded ash clearwing (Podosesia aureocincta) and the ash/lilac borer (Podosesia syringae) are Native Ash borers, two species of moth that produce larvae that bore into the wood of the ash tree, seriously weakening it structurally and making the ash more susceptible to damage from other insects and disease. The larvae produce exits holes in the wood of approximately 1/4 inch in diameter and expel frass -- a combination of sawdust and insect excrement -- from the tree.

Borer Description

• Dependent on their sex, the wasp-like, adult clearwing borers possess different colors ranging from orange, red, yellow, black and blue. The adult clearwing moth emerges in the spring and lays eggs on the bark of the ash tree, while the adult banded moths fail to appear until August. The mature moths live only a few days and do no damage to an ash tree. Instead, as with most borers, the hungry larvae left behind feed on the specimen.