Plants suddenly wilt because the stem is hollowed out or cut off at or just below ground level. The cutworms can usually be found in the soil within a few centimetres of damaged plants. There are a number of species of cutworms and they may be gray to dark brown in colour and striped or mottled. Mature cutworms are about 3.5 cm long. Insecticide application is not recommended in this case because most of the damage is done and it is better to wait a few days and replant.
Treatment is most effective when applied soon after cutworms have hatched.
Only a small acreage of Ontario corn has cutworm problems in any one year. For this reason, and because corrective sprays are available, granular treatments applied at planting time are not recommended. Factors that favour cutworm outbreaks include a history of cutworm damage, late planting, broadleaf weed infestations occurring prior to tillage and planting, and surface residue, especially soybean residue. Cutworm moths do not overwinter in Ontario, but are blown in from the south on strong southerly weather systems. Therefore, cutworms are more frequent in fields with green cover early in the spring before primary tillage.