Black Cutworm Fact Sheet from OMAFRA

An unseasonably early tornado season in the U.S. Midwest has blown a potentially big black cutworm problem to southern Ontario farms. 

Scientific Name
Agrotis ipsilon

Identification

• Black cutworm larvae are greyish-black with a paler underside 
• Mature larvae are about 5 cm (2 in.) long
• The larvae are soft and fat, and they roll up when disturbed 
• Early-season cutworms attack the seedling plants, usually cutting them below or at the soil surface 
• A single larva may destroy several seedlings

Often Confused With
Wireworm damage
Damping-off

Period of Activity
Warm, clear, calm nights in early spring are ideal for moths to lay eggs. Feeding occurs from early May through to mid-June. Larval activity usually coincides with early season planting and emergence.  Damage is often sporadic and appears in localized areas within a field. Most species of cutworms feed at night, hiding during the day under loose stones or in the soil near the base of the plant. Plants are most vulnerable to cutworm losses shortly after transplanting.

Scouting Notes
While walking fields, keep an eye open for wilted plants or stems that have been severed at the soil level.  Dig around the damaged plant to look for the cause of the damage.  If a cutworm is uncovered, take note of its size.  Record the percentage of wilted or cut plants within the field.

Thresholds
For most vegetable crops, the control guideline is 5% damaged plants. Small larvae (less than 1 cm or 3/8 in.) are easier to control. Large larvaestop feeding as they prepare to pupate.  Control of these large larvae is usually unnecessary.

Check the OMAFRA fact sheet at: http://www.omafra.gov.on.ca/IPM/english/peppers/insects/black-cutwo...