Cutworm Pictures

• Lacanobia
• Bertha armyworm
• Cutworm feeding damage

Lacanobia subjuncta occurs throughout North America and is reported feeding on a wide range of plants including several crops. In recent years larvae of this insect have become more common in commercial apple orchards and in some have caused considerable fruit injury. Because this insect is relatively new as a problem in orchards this web site was constructed to provide up to date information on the identification and damage it causes.

There are two generations of L. subjuncta in WA. It overwinters as a pupa in the soil and adults emerge in May and June. Larvae are present in June feeding on foliage when young and on fruit and foliage when older. Larvae will remain in the tree unlike other cutworms, which return to the ground and only feed in trees at night. When larvae are young they are light green with a white stripe along the side. As larvae grow they transform into a light brown color with darker markings on the upper surface. Larvae are voracious feeders and can defoliate shoots in a few days. A second generation occurs in July and August with larvae feeding on foliage and fruit in August and September.

Dr. Peter Landolt, USDA-ARS in Wapato, has identified a pheromone for Lacanobia subjuncta. This pheromone was used this summer to monitor seasonal activity but is so attractive that it is not useful for determining population densities within orchards. Growers and crop consultants must use visual examination of shoots for feeding or beating trays to dislodge larvae in order to determine the need to apply controls.

In preliminary chemical control tests conducted in 1998 Lorsban and Lannate provide the best control of Lacanobia subjuncta of the materials tested. Growers have also reported Thiodan as being effective. Lannate can result in suppression of predatory mites and disruption of integrated mite management so caution should be exercised when using this product. Additional insecticide screening tests are underway and will be reported when completed.