Ag Line: Cereal Leaf Beetle on Wheat
By Wade Parker County Extensio Coordinator

CEREAL LEAF

As one would expect, high wheat prices seem to bring on every pest in the book! This past week, I identified some cereal leaf beetle larvae in wheat. In the past, cereal leaf beetle larvae have been contained to the northwest area of the state. With the passage of time, this insect is spreading southward and now occurs throughout the coastal plain. Cereal leaf beetle larvae feed on many grasses including many oats, wheat, barley, rye, and annual ryegrass, but the insect is mainly a problem on oats and wheat.

Adult beetles are 5 mm long and blue-black with a reddish thorax and legs. Larvae are yellow- white and up to 6 mm long, but appear shiny and black because they are covered with fecal material. Adults and larvae defoliate, or skeletonize, long narrow sections of the flag and upper leaves. Adults are present in wheat during March and April when they mate and lay eggs. Larvae are also present during head emergence through the dough stage of wheat development, which typically occurs in late March and early April. Larvae damage reduces grain yield and test weight mostly by reducing seed size.

Yield losses usually do not occur until flag leaf defoliation exceeds 50 percent. Cereal leaf beetles can be effectively controlled by one application of an insecticide per year. Fields should be scouted by counting the number of larvae and adults on 10 stalks at 6 to 10 locations per field. Treatment should be considered when populations exceed one larva per two stems. Many farmers are in the process of making plans to apply a fungicide in the next few days. This would be a perfect time to apply an application of Karate, Warrior, Mustang Max, etc. These insecticides will also provide adequate control of aphids and cereal leaf beetles.

The next week or two will be very important for the wheat crop. Keep an eye on your fields and call if you have any questions.

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