Clover cutworm
Dicestra trifoli
Clover cutworms overwinter as pupae in the soil. There are two generations per year. The first moth generation appears in June, the second in late July. The adult moths are uniform or mottled ash grey to pale brown. White or pale yellow eggs are laid singly on the undersides of leaves in late spring and during the summer. The newly hatched light green caterpillars feed on the undersides of lower leaves, gradually moving up the plant as they mature, causing damage during late June through early July and again from mid- August through to September.
Clover cutworm larvae are very similar in appearance and size to bertha armyworm larvae, but fewer velvety black caterpillars are found and the majority are either green or pale brown. The most distinct difference between the two species is the wide stripe along each side of the clover cutworm is yellowish pink and yellowish orange on bertha armyworm. Mature caterpillars burrow into the topsoil to pupate. The pupa is somewhat smaller than that of bertha armyworm, and has a greenish tinge at one end. Most of the pupae formed in mid-summer emerge to produce the second flight of moths. The second-generation larvae frequently cause damage at the same time as bertha armyworm (August 10 to 30). In years when both are present, clover cutworms may be mistaken for bertha armyworm. This insect has only been an economic problem in the Peace River area of Alberta.