Larvae are yellow-white and up to 6 mm long, but appear shiny black because they are covered with fecal material. Adults and larvae defoliate or skeletonized 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 present in April and May during head emergence through the dough stage of wheat development. Larvae damage grain yield and test weight mostly by reducing seed size.
Wheat can tolerate considerable defoliation.
Cereal leaf beetle can be effectively controlled by one application of an insecticide to foliage. 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 made after most eggs have hatched but before larval damage becomes extensive. Sampling For Insect Pests Wheat should be scouted weekly from the time it is planted until it is mature. Damaging levels of insect populations and resulting injury can be expected to be more severe during periods of mild weather.