WSU Extension


Oak : Oak ribbed casemaker
(revision date: 6/24/2015)

Oak ribbed casemaker larvae mine and skeletonize leaf tissues. Young larvae feed inside leaves, chewing away tissues and leaving a linear mine. Older larvae feed on the underside of leaves, leaving only the upper surface and veins, which turn brown. Severely damaged leaves may be almost transparent. The mature larvae are about 1/4" long, and pale yellow to green. Immature larvae make flat, white, circular cocoons, while cocoons of mature larvae are white, with distinctive longitudinal ribs. The latter can be found on leaves, twigs, or other nearby objects. The adult moth emerges from the ribbed cocoons. It is mottled white, brown, and black with a wingspread of about 1/3". The oak ribbed casemaker is reported on California white (valley) oak (Quercus lobata) and coast live oak (Q. agrifolia).
Management Options

Non-Chemical Management
  • Natural enemies probably help keep populations in check. Avoid use of broad-spectrum insecticides which kill beneficial insects.
Select non-chemical management options as your first choice!

Chemical Management

Apply in summer when caterpillars are first active. Bacillus thuringiensis (Bt) will control leafrollers only if they are actively feeding. Use a spreader-sticker with liquid Bt formulations. Homeowners should not make foliar applications to trees over 10 ft tall. Consult a commercial pesticide applicator for treatment of trees and shrubs over 10 ft. tall.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • Safer Brand Caterpillar Killer for Trees, Shrubs & Vegetables Conc II [Organic]
    Active ingredient: Bacillus thuringiensis subsp. kurstaki  |  EPA reg no: 70051-106-42697
  • Safer Brand Caterpillar Killer/Trees, Shrubs, & Vegetables Conc
    Active ingredient: Bacillus thuringiensis subsp. kurstaki  |  EPA reg no: 42697-23
  • This list may not include all products registered for this use.
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Caption: Oak ribbed casemaker
Photo by: A.L. Antonelli