Origin:
It is believed that this moth originated in Asia and moved into Europe many centuries ago. It was then brought into North America in infested materials during colonial times and was discovered on the Pacific Coast states by 1872. It now is found worldwide wherever suitable host plants are grown.
Biology:
This is the usual “worm in the apple” species of moth, but the larvae also infest pears, apricots, peaches, and walnuts. It has the potential to destroy or damage nearly all of the crop on a single tree. The adult moths are active from April through November in warmer regions, and females can lay eggs throughout the summer months, extending the period when control efforts are required. The final larva overwinters in a cocoon attached to the bark of the tree or in plant debris below the tree, pupating in early spring. Adults emerge a short time later and begin depositing eggs on stems or young fruit. The larvae burrow to the center to feed around the seeds and then burrow out prior to pupating, leaving noticeable holes and damage as well as encouraging rotting of the fruit. There may be up to 4 generations each year.
Identification:
The presence of the larvae is indicated by the holes in the fruit or husk of the walnut. The larva is white to pink in color and about ½ inch long when mature. Adult moths are gray with darker lines and spots on the forewing and with a distinctive coppery-brown wide patch at the end of each forewing. When at rest they hold their wings tent-like over the abdomen.
Characteristicts Important to Control:
Sanitation is important in overall management of this moth, removing plant debris under trees during the winter to remove any overwintering cocoons as well as removing fallen fruit during the season and any fruit on the tree that appear to be infested. For backyard trees the developing fruit can be enclosed in mesh bags to exclude the female moths. Pheromone traps exist for monitoring or for reducing the numbers of adult moths. Insecticide applications often are needed and carbaryl is considered to be one of the most effective. The first application needs to be applied after most blossoms have fallen and the tiny fruit have appeared, with repeated applications through the season.
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