How to Manage Pests
UC Pest Management Guidelines
Western Tussock Moth
Scientific name: Orgyia vetusta
In this Guideline:
The full-grown western tussock moth larva is 1.5 to 2 inches in length, generally gray in color with numerous colored
spots, four prominent white tufts of hair on its body, and two black tufts on
its head and one on its posterior end. The adult female moth is wingless and light silver gray. Males are winged and also gray in color.
Larvae appear in spring and become adults in May, June, and July. These adults
produce caterpillars that feed for 40 to 60 days before they pupate.
There are two generations of tussock moth in southern California, but only one
in northern California.
The caterpillars feed on foliage and young fruit, devouring large
portions of leaves or entire leaves, and making irregular holes in the fruit.
Natural enemies usually keep tussock moth under control.
Organically Acceptable Methods
thuringiensis sprays and pruning out infestations are organically
acceptable management methods.
Monitoring and Treatment Decisions
trees, cut out and destroy infested twigs. Spray programs for other insects
generally reduce populations. If insecticide treatments are required, localized
treatments on individual trees and branches are generally all that is
necessary. Treat when small caterpillars are first observed. The addition of a
wetting agent to increase penetration of the webbing by the insecticide
||Amount to Use**
choosing a pesticide, consider information relating to impact on natural enemies and honey bees, impact of timing on beneficials, and environmental impact Not all registered pesticides are listed. Always read label of product being used.
||BACILLUS THURINGIENSIS spp. KURSTAKI#
||MODE OF ACTION GROUP NUMBER1: 11.B2
||COMMENTS: Most effective on small caterpillars. Does not destroy natural enemies.
UC IPM Pest Management Guidelines: Plum
UC ANR Publication 3462
Insects and Mites
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
K. R. Day, UC Cooperative Extension, Tulare County
Acknowledgment for contributions to Insects and Mites:
R. E. Rice, Kearney Agricultural Center, Parlier
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