Hosta growers, vegetable gardeners and others had a tougher time than usual this spring with one of our less common pests, the variegated cutworm . The variegated cutworm is found in sites as varied as alfalfa fields to home gardens. A nickname for this species is "climbing" cutworm because of its habit of climbing plants at night to feed on foliage, flowers, buds and fruits. Variegated cutworms do not damage plants by clipping at ground level as is usually typical of cutworms.
Nearly all fruits, vegetables and ornamental plants can be damaged by variegated cutworms. Damage is especially common on hosta, petunia and other low growing, "fleshy-leafed" plants. Feeding on hosta foliage causes large irregular holes at the leaf margins or oblong holes within the leaf bounded by veins. Destruction of emerging leaves at the center of the crown can be nearly complete.
This year's abundance is probably connected to our past winter weather (snow cover?) and the wet spring weather.
The variegated cutworm has the typical cutworm appearance (dark, smooth, hairless caterpillar with a "pudgy" appearance). This cutworm can be distinguished from other species by a characteristic row of 4 or 5 yellowish-white dots down the middle of the back, one spot per body segment.
Variegated cutworms large enough to cause noticeable damage are usually at least 1/2 to 3/4 inch long. They ultimately grow to be 1 1/2 inch. Like other cutworms, variegated cutworms are nocturnal and feeding takes place at night or on very cloudy days, meaning few people have seen the cutworms though many are familiar with the large irregular holes noticed later.
Control can be as simple as raking around the base of damaged plants with your fingers until you find the culprit. The brown cutworms blend well with the color of mulch and soil and careful searching will be necessary. Searching for cutworms at night and discarding all that are found feeding on plant foliage is another possible mechanical control. Larger problems with variegated cutworms can be controlled by treating the soil around damaged plants with Sevin, permethrin or diazinon.
This article originally appeared in the June 15, 2001 issue, p. 73.
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