Host Plants:
On Crops: Lettuce, cabbage, beans and almost any young vegetable and plant seedlings
Where Found:
Common wherever vegetables are grown
Description:
Although there are other species of moth whose larvae are commonly called cutworm, the turnip moth is the main species. Adult moths have pale brown forewings with dark brown edges whilst the hindwings are a pearly white colour. They have a wingspan of around 4cm and can be found on the wing between May and July. Turnip moth larvae are plump and have a smooth skin which is browny-grey in colour. These larvae hide in the soil during the day and feed at night. Wilted plants that appear to have been cut off at the soil line are the sure evidence of cutworms. The damaged plant is usually left lying on the soil’s surface.
Damage:
Larvae feed on roots and foliage starting in late spring, but damage increases as the larvae gain in size and appetite. In dry summers, cutworms can crawl up plants and chew holes in the foliage that look like damage done by slugs.
Preventing Problems:
Cutworm collars which are 5-7cms across, pressed 2.5cm into the soil around vulnerable plants, are usually effective. They can be made of cardboard, metal cans, or plastic drink cups cut into rounds. Gently digging or hoeing around the base of susceptible plants will often expose cutworm larvae to insectivorous birds such as robins.
Managing Outbreaks:
As soon as you suspect cutworm damage, use a fork and flashlight to find the culprit at night; one individual cutworm can do significant damage. Check at hourly intervals at night and you can catch them as they show themselves.
Tips:
Frequent shallow cultivation can expose and kill cutworms. Attract insect-eating birds by providing convenient perches nearby.
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