How to Manage Pests
UC Pest Management Guidelines
Western Tussock Moth
Scientific name: Orgyia vetusta
In this Guideline:
DESCRIPTION OF THE PEST
Western tussock moth overwinters in the egg stage, and larvae begin
emerging in March and April. Immature
larvae are hairy and black. Mature western tussock
moth larvae are
large (almost 2 inches in length) caterpillars with numerous red and yellow
spots and long tufts of hair. There are four white tufts of hair on the top of
the first four abdominal segments, two black tufts on the head, and many
grayish tufts over the body. Adult
females are large, wingless, and predominantly gray. The males are winged moths. There is only one
generation per year.
As the tree begins to leaf out, larvae feed on the foliage.
Localized heavy populations can completely defoliate trees.
Visually search trees for black caterpillars feeding on terminal
growth and look for cocoons on major scaffolds. Insecticides applied for plant
bug control will reduce western tussock moth populations.
Organically Acceptable Methods
Sprays of Bacillus thuringiensis are acceptable for use in an organically managed
|When choosing a pesticide, consider information relating
to impact on natural enemies
and honey bees and environmental impact Not all registered pesticides are listed. Always read label of product being used.
||BACILLUS THURINGIENSIS ssp. KURSTAKI#
||MODE OF ACTION: A microbial (Group 11.B2)1
UC IPM Pest Management Guidelines: Pistachio
UC ANR Publication 3461
Insects and Mites
W. J. Bentley, Kearney Agricultural Center, Parlier
R. H. Beede, UC Cooperative Extension, Kings County
K. M. Daane, Biological Control, UC Berkeley/Kearney Agricultural Center, Parlier
D. R. Haviland, UC Cooperative Extension, Kern County
Acknowledgment for contributions to Insects and Mites:
R. E. Rice, Kearney Agricultural Center, Parlier
Top of page