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Cereal Leaf Beetle
Order: Coleoptera
Family: Chrysomelidae
Scientific name: Oulema melanopus (L.)
Common name: Cereal leaf beetle (CLB)

Adults: Deep metallic blue to blue-green wing covers with red area behind the head and red legs, shiny black underneath and about 3/16.

Eggs: Bright yellow when fresh changing to dark amber when developed, eggs are smooth, oval, and a little less than 1/16 inch long. Eggs are laid on the upperside of the leaf close to the base and parallel with the leaf veins. They are usually laid singly or two together but sometimes five or six are laid in a row.

Larvae: Full size larvae are 3/16 to 1/4 inch long and lemon yellow. One may not see the yellow color because they are normally covered with a layer of slime in which the larvae put their fecal matter. The shiny, blackish covering makes them look very slug-like. A walk through an infested field will leave hundreds of small dirty spots on your clothing.

Pupae: The pupal stage is generally not seen because the larvae pupate in the soil inside earthen cocoons about 1 to 2 inches deep.
clb larvaeclb larva with parasiteclb adult

Damage: The adults and larvae feed on leaves of winter wheat and spring grains. The adults chew slits through the leaves, parallel to the leaf veins. Like the adults, the larvae feed parallel to the leaf veins but feed only on the surface of the leaves creating a frosted “window pane” effect.

Impacts: Early spring adults and larvae usually do little damage to winter crops. However, spring planted grains, especially oats and barley, can be heavily impacted by the larval feeding, resulting in stunted growth and reduced grain yields because adult CLB prefer to lay their eggs on lush new spring grains.

Host plants: CLB hosts include oats, barley, wheat, and to a lesser degree corn, timothy, rye, triticale, sorghum, millet, orchard grass, quackgrass, reed canary grass, bluegrass, fescue, rice, brome, mouse barley, and foxtail.

Distribution: The beetle has been reported in more than 22 states east of the Mississippi as well as Iowa, and Missouri. Western states now infested with CLB include Washington, Oregon, Idaho, Montana, Wyoming, Colorado, and Utah.
distribution map
Biology and Life Cycle: Cereal leaf beetle has one full generation per year and overwinter as adults. In mid-March to early April, adults emerge from hibernation and begin to feed on available winter wheat or other suitable grasses in a similar growth stage. They then move onto spring grains where they continue feeding and lay the majority of their eggs. Adult mating and egg laying occurs mostly from mid-April through May and the larvae develop mostly from mid-May to late June. Larvae then pupate in the soil and quickly develop into adults that emerge by mid-July. Summer adults will feed briefly on any suitable host grasses, including corn, before seeking protected areas where they hibernate until the following spring.

What ODA is doing: ODA, in cooperation with USDA and OSU, has been part of an extensive biological control program since the beetle was found in the state. Parasitic wasps that specifically target the larvae of cereal leaf beetle are released in suitable fields. Some fields in recently infested counties are monitored for suitability as biocontrol collection or release sites. Biocontrol sites are selected based on having high CLB populations and limited or no pesticide use.

How you can help:
  1. If you are a grower of cereal grains in one of the uninfested counties and believe you have seen cereal leaf beetles or the larvae and damage in your field(s), please contact ODA at 503-986-4636 or 1-800-525-0137 to talk to an entomologist.
  2. Cooperate with Oregon Department of Agriculture or USDA staff when they perform seasonal detection surveys or biological control work.
  3. Observe quarantine regulations by not moving restricted materials out of cereal leaf beetle infested areas without certification.

CLB flyer, pdf

Photo credits:
Adult beetle: USDA-APHIS