The beetle's feeding damage before boot stage causes a loss of plant vigor. After boot stage, they feed primarily on the flag leaf, affecting seed set and grain test weight. An average of more than one larvae per plant can cost five to six bushels of grain and warrants treatment. Several products are registered for cereal leaf beetle control, but watch harvest restrictions since you may be treating close to head and grain formation. The MSU Cooperative Agricultural Pest Survey will continue to monitor for the cereal leaf beetle to detect its spread.
Most fields are about four to six inches.
This is too short to use a sweep net effectively, but you may see small weevil larvae near plant terminals. At this point they feed in the growing point of the plant, causing a shothole pattern as the trifoliate expands. At this stage they are less than half an inch long but growing fast. The small larvae are pale yellow with black heads, not their later bright green with a white stripe down the middle of the back. Within two weeks you should be able to use a sweep net for sampling.