Tomato pinworm is an unusual pest of tomatoes and eggplant for New Jersey as it is typically found in the southwestern states. It can be transported on transplants but is probably capable of spreading to new locations with weather fronts. Tomato pinworm was found in Somerset and Morris Counties in fields and high tunnels. This week an infestation was found in a field in Cumberland County. This would suggest that we have a state-wide infestation. Undoubtedly these infestations are in part due to the unusually warm winter and spring we experienced. Pinworm cannot overwinter in New Jersey.
The pinworm moth is a small, greyish-white with small dark, insect that lays it eggs singly on the underside of leaves of the tomato. When the eggs hatch the caterpillars begin feeding within the leaves creating a blotch leafmine. This will be a papery appearing section of the leaf where the caterpillar has eaten the tissue between the upper and lower leaf cuticles. As the caterpillars grow they leave the leafmine and invade fruit, attacking the calyx and stem area but also borrowing into the rind anywhere. The tunnels are short and occur almost entirely in the rind. The holes appear similar to tomato fruitworm (corn earworm) damage, but the pinworm holes are much smaller. Mature caterpillars may create a mine under the cuticle of the fruit. The caterpillars will drop to the soil and make loose cocoons to complete their development to the adult stage. There are multiple generations a year.
Pictured is a medium sized pinworm caterpillar, about 1/4 inch long. Mature caterpillars are white or yellow with purple markings and are about 3/8 inch long.
Joe Ingerson-Mahar