Loopers

Looper caterpillars are easily recognized because they crawl by arching their backs. Looper eggs are laid singly on the undersurface of mature leaves. They are similar to fruitworm eggs, but flatter, and have finer ridges radiating from the top.

Loopers feed only on foliage, not on fruit. Damage is not serious enough to require control measures so treatment is rarely recommended.

Although common in tomato fields, looper populations are generally kept below damaging levels by naturally occurring parasites and a viral disease. Moderate numbers of loopers are considered more beneficial than harmful because they serve as alternative hosts for parasitic wasps that also attack tomato fruitworms and other pest caterpillars. Treatment is only necessary if feeding is extensive enough that sunburn of the fruit is a concern. When insecticides are required, consider nondisruptive insecticides such as Bacillus thuringiensis to protect natural enemies.

There are several important naturally occurring parasites that help control loopers in tomatoes. One of these is Hyposoter exiguae, which also attacks tomato fruitworms and armyworms. Another parasitic wasp, Copidosoma truncatellum, commonly kills looper and other lepidopteran larvae by attacking the overwintering pupae. In southern California, looper eggs are often killed by Trichogramma; Trichogramma released for tomato fruitworm control often parasitize cabbage looper eggs as well. Alfalfa and cabbage loopers are also subject to disease caused by a nuclear polyhedrosis virus. Conserve these parasites by not treating with disruptive pesticides, particularly early in the season.

Biological control and sprays of Bacillus thuringiensis or the Entrust formulation of spinosad are acceptable for use on an organically certified crop.

Determine the extent of damage in the field. If damage is severe enough to expose fruit to sunburn, treat when tomatoes are at mid- to late-stage vegetative growth to maintain the plant canopy. Spot treat only severely infested areas.