How to Manage Pests
UC Pest Management Guidelines
Scientific Name: Loxostege spp.
(Reviewed 11/06, updated 8/15)
In this Guideline:
DESCRIPTION OF THE PEST
Webworms are dark green caterpillars with two white stripes and black spots on their backs. They are often found within webbed leaves. They vary in size up to almost 1.5 inches in length.
Webworms overwinter as larvae in the ground adjacent to their fall food host. Moths emerge in early spring and lay eggs on leaves of host plants. Larvae will feed for 3 to 5 weeks.
The larval stage feeds inside of webbed leaves on the upper parts of the plant in summer and fall. If numbers are abundant, this webbing will be clearly visible and will cover extensive areas of foliage.
Early cutting may give satisfactory control. Treatment is rarely justified in California.
UC IPM Pest Management Guidelines: Alfalfa
Insects and Mites
L. D. Godfrey, Entomology, UC Davis
Acknowledgment for contributions to Insects and Mites:C. G. Summers, Entomology, Kearney Agricultural Center
M. Rethwisch, UC Cooperative Extension, Riverside County (Blythe)
D. R. Haviland, UC Cooperative Extension, Kern County