Order:    Lepidoptera

Family:    Lymantriidae

Latin Name:    Orygia leucostigma (J.E.Smith)

Common Name:    Whitemarked Tussock Moth

Introduction
Top

The larva stage of this insect can cause serious defoliation in forested stands of balsam fir. In Christmas tree stands, it is a greater problem because of export hindrances as well as defoliation damage.

Life History
Top

This insect overwinters as eggs within an egg mass. The eggs hatch from late June to early July. The larvae migrate to the leaves or needles and consume everything except the main veins. The larva is full grown in about five weeks and is approximately 35mm long. It has a reddish-orange head and a dark hairy body with white lines running lengthwise. There are four distinct greyish tufts of hair on their backs. When mature, the larva spins a dark grey cocoon and pupates. The cocoons can be found on twigs, branches, or bark. Adults emerge from late August to early September. The male moth is ash grey with a wingspan of 26 - 30 mm and the female is dirty white, hairy, wingless and about 13 mm long. Eggs are laid on or near empty cocoons.

Damage Symptoms
Top

The young larvae skeletonize the leaves of hardwoods, the older larvae consume the entire leaf except for the main veins and petiole. On conifers, the needles are consumed, and occasionally the tender bark is chewed. They tend to feed on the upper third of the tree first.

Control Options
Top

Large forested areas can be protected by aerial application of Btk. In Christmas tree stands, either Btk or contact chemical insecticides can be applied with good success.