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Western Tussock Moth Description:

The western tussock moth is considered a pest and commonly found on the Pacific coast from southern California up to British Columbia.

Hosts:

This pest feeds on willow, hawthorn, manzanita, oak, walnut, crabapple, pyracantha, California holly, coffeeberry, and other plants.

Biology and Symptoms:

In southern California, two generations may occur each year. Other areas may have only one generation per year. In northern California, this insect lays eggs in summer in felt-like masses, usually on old cocoons. These grayish-brown masses are typically 1/4” to 3/8” in diameter. The eggs hatch early the following spring. The larvae (caterpillars) are attractively colored, with spots of red and yellow, and four rounded, brush-like tufts on their backs. The young larvae skeletonize the leaves, while more mature larvae eat entire leaves. They remain caterpillars for 40 to 60 days and can become a nuisance when they wander to find a place to pupate. The adults emerge the same year as the cocoons are formed (pupation). The adult females are wingless and silvery-gray, while the males have wings and are grayer in color.

Management:

If necessary, pesticide applications during the early stages of larval feeding may help control the pest. Ask an arborist about the best treatment options for your property.

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