The case of the bertha armyworm and the clover cutworm (and other cutworm species)
Are those bertha armyworms (Mamestra configurata) eating your canola, mustard or alfalfa (also found on lamb’s-quarters, peas, flax, potato)? Or is it maybe a clover cutworm (Discestra trifolii)? [Note: not all cutworm species spend their larval stage underground.] The larvae of the two species are doppelgangers as they are similar in appearance, have a large overlap in host crops, and have similar timing (June-September). Telling them apart can be a challenge but here are few tips to focus on to help distinguish:
- there are generally fewer velvety black clover cutworm caterpillars, with most of the clover cutworm larvae being green or pale brown
- On the clover cutworm it is yellowish-pink
- On the bertha armyworm it is yellowish-orange
In terms of scouting, economic thresholds and control options, treat both species as you would bertha armyworms.
To learn more about bertha armyworms and clover cutworms, go to the Insect of the Week page or download copies of the Field Crop and Forage Pests andtheir Natural Enemies in Western Canada and Cutworm Pests of Crops onthe Canadian Prairies identification field guides.