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.
In areas where tomato pinworm is a common threat, mating disruption and biological control methods can be used to help minimize damage. In New Jersey, insecticides are the only reliable means of control. The 2012 Commercial Vegetable Recommendations includes several materials that should provide control. For more information on tomato pinworm go to: http://ipm.ncsu.edu/ag295/html/tomato_pinworm.htm, and, http://www.ent.uga.edu/veg/solanaceous/tompinworm.htm