IPMP3.0, Oregon State University, Copyright 2000





Sampling and Action Threshold

Development Model

Registered Insecticides


[Insect Management]


Variegated Cutworm Egg Mass Variegated Cutworm Larva

Variegated cutworm, Peridroma saucia, is a common pest of many vegetable and field crops, including mint. They overwinter as half grown larvae in soil or under plant debris in or around mint fields. Larvae begin feeding in April and mature in late April and May. Larvae pupate in earthen cells in the soil. Adults emerge in May and early June and deposit eggs in clusters of 200 to 500 on the undersides of leaves. Eggs hatch in 4 to 7 days and larvae begin feeding on plant foliage. Larvae feed for 4 to 6 weeks and then pupate in the soil. Larvae cause the most damage to mint in late July and early August. Summer generation adults emerge in late August and deposit eggs. Larvae hatching from these eggs feed until cold weather and then become inactive and overwinter. There are two overlapping generations each year. In IPMP3.0, there is a variegated cutworm development model, and a variegated cutworm economic threshold program. See also the section on variegated cutworm management and control.

Often the larvae of other species occur on and defoliate mint at about the same time as the variegated cutworm. Bertha armyworm, Memestra configurata, is often seen in mint fields, particularly west of the Cascade Mountains. Its life cycle is about the same as that of the variegated cutworm. However, at times Bertha armyworm larvae may be present before detectable populations of variegated cutworm. Because its leaf feeding damage usually occurs earlier in the growth of mint and its population density is generally less than that of variegated cutworm, it is important to distinguish between the two species. An early insecticide application against this species may not necessarily control variegated cutworm. One well-timed remedial application for cutworms and loopers reduces cost and pesticide load on the field, and minimizes other possible problems, such as the induction of spider mite problems, destruction of beneficial insects, and increased pressure for resistance development in pest insects.