Oak (Quercus)-Oak skeletonizer

Oak skeletonizer (Bucculatrix ainsliella)

Oak-ribbed skeletonizer (Bucculatrix albertiella)

Pest description and damage This insect also is known as the oak ribbed casemaker (Bucculatrix albertiella). The adult moth is mottled white, brown, and black with a wingspread of about 0.33 inch. The mature larvae are about 0.25-inch long and pale yellow to green. 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 oak ribbed casemaker is reported on California white (valley) oak (Quercus lobata) and coast live oak (Q. agrifolia).

Biology and life history This insect appears to pass the winter inside its characteristic cocoon. Immature larvae make flat, white, circular hibernating cocoons, while cocoons of mature larvae are oblong and white with distinctive longitudinal ribs. The latter are found on leaves, twigs, or other nearby underlying objects. It is easy to transport this insect stage from place to place with infested plant material. The moths appear in spring and lay eggs on the undersides of leaves. The larvae emerge and feed on the foliage. There are two generations per year.

Management-biological control

Natural enemies probably help keep populations in check. Avoid use of broad-spectrum insecticides that kill beneficial insects.

Management-cultural control

Rake up fallen leaves to remove cocoons; destroy by deep composting.

Management-chemical control

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