Speckled Green Fruitworm
- Fruit trees
- Ornamental trees such as willow, birch, poplar, alder, and maple
In Utah, the speckled green fruitworm (Orthosia hibisci) is a common pest of fruit trees. The larvae (caterpillars) hatch in spring and begin feeding on buds, flowers, leaves and young fruit.
The speckled green fruitworm spends the winter as a pupa in the soil. Adult moths emerge in April and May and lay egg masses (100-300 eggs each) in the tree canopy. The moth is stout, reddish brown (approximately ¾-inch long, ½-inch wide) with subtle spotting on the wings. Larvae begin hatching in late April in northern Utah, and are present through June. There is one generation per year.
The larva has a lime-green head, and pale green body with white speckles, and white lines running along its back and sides. This coloration allows it to hide amongst leaves and young fruit.
- Localized defoliation
- Early-season fruit damage
- Severe malformation of mature fruit
Speckled green fruitworms are generally not a problem where insecticides are applied for other fruit insect pests. They are easily suppressed with the bacterial insecticides Bacillus thuringiensis (Bt) (many formulations) and spinosad (Success, Entrust, Conserve), and most broad-spectrum insecticides.