Weedy fields where postemergence herbicide treatments are used often become infested with maggots as dead weeds decompose. Inspect these fields daily for flies and maggots a couple of weeks after herbicide use. The immature stage known as a nymph has the same markings but is smaller and more round. The eggs stand on end in double rows and appear as tiny white kegs with black hoops. The harlequin bug can cause serious damage to crucifers and other vegetable crops.
Younger plants are more susceptible to the feeding.
Larger plants can withstand higher populations but show reduced growth and yellowing. B.t. is a microbial insecticide that contains spores of these bacteria and is used to control caterpillars when they feed on leaves containing the spore s. Aphids may be controlled using malathion or diazinon or a commercially prepared insecticidal soap product. Harlequin bugs can be controlled using Thiodan. Read and follow all label directions on recommended pesticides.