Whitemarked Tussock Moth

Order: Lepidoptera

Family: Lymantriidae

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

Common Names: Whitemarked Tussock Moth


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

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

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

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.


CAUTION: Read and follow the instructions on the label when using any control agent. Proper application and use of recommended personal protective equipment are essential for the safe use and effectiveness of any pesticide.

DISCLAIMER: Control options are suggestions only. Actions taken for pest control are the sole responsibility of the applicator in full compliance with any Federal, Provincial or Municipal Acts, Regulations or Bylaws.