Green fruitworm (Lithophane antennata)
Pyramidal fruitworm (Amphipyra pyramidioides)
Pest description and crop damage Several species of green fruitworms can attack fruit trees. These also are found feeding on a wide range of hosts such as willow, birch, alder, maple, strawberry, and other tree fruits. Adult fruitworm moths vary depending on the species but are generally large, with gray to reddish-brown wings, and are attracted to lights in the fall and spring. Immature larvae are similar to cutworms, with green bodies and heads. Mature larvae are green with white or cream longitudinal stripes.
Green fruitworm larvae feed on flowers and leaves, occasionally tying them together with silk. When the larvae increase in size, they begin feeding on the fruit, starting inside the cluster and taking bites out of most fruit in the cluster. Badly damaged fruits drop, and damaged fruits that remain have large, russeted cavities.
Biology and life history Depending on species, the insect may overwinter as a pupa in the ground or as a fertilized female moth on the soil surface. In the spring, eggs are laid on the twigs, often before buds open. The eggs hatch at the pink stage, and young larvae feed on the flowers and leaves, and later on the leaves and fruit. When the larvae mature, they drop to the soil to pupate. Depending on species, they remain as pupae through the winter or emerge as adults in fall, mate, and the females overwinter.
Scouting and thresholds Examine fruit clusters shortly after fruit set for the small green larvae. They tend to occur in clumps, so thorough monitoring is required.
Birds often are seen eating green fruitworm larvae. Ground predators probably reduce pupal or adult overwintering populations. Some parasitic wasps are also important.
Adults can be collected in black-light traps. Hand-pick larvae when thinning fruit.
Management-chemical control: HOME USE
Stages 5-6: Pink spray
- azadirachtin (neem oil)-Some formulations are OMRI-listed for organic use.
- carbaryl-Highly toxic to bees.
- esfenvalerate-Highly toxic to bees.
- gamma-cyhalothrin-Highly toxic to bees.
- kaolin-Applied as a spray to leaves, stems, and fruit, it acts as a repellant to some insect pests. Some formulations are OMRI-listed for organic use.
- lambda-cyhalothrin-Highly toxic to bees.
- permethrin-Highly toxic to bees.
- pyrethrins-Highly toxic to bees. Some formulations are OMRI-listed for organic use.
- zeta-cypermethrin-Highly toxic to bees.
Management-chemical control: COMMERCIAL USE
Stages 5-6: Pink spray
- Bacillus thuringiensis (Dipel, Javelin, etc.)-Formulations vary; see label for rates. Apply Bt materials two to three times, beginning at prepink, repeating at pink and petal fall. Apply Bt when temperature exceeds 60°F. REI 4 hr. Some formulations are OMRI-listed for organic use. [Group 11] [larvicide]
- flubendiamide (Belt SC) at 3.0 to 5.0 fl oz/a in a minimum of 100 gal water per application. Do not exceed three applications per growing season. REI 12 hr. [Group 28]