Grape Tomato Gall, Lasioptera vitis Osten-Sacken
Several species of small flies, or midges, are known to cause galls on various parts of grapevines. The adult flies lay their eggs either on or in leaves, leaf petioles, tendrils or cluster stems. Fleshy or blister type galls, depending on the species of fly, are formed when the eggs are deposited inside the plant or when the larvae emerge from the eggs and begin to feed. When these larvae are fully grown, they leave the galls, fall to the soil and pupate. Some species may have more than one generation per year.
The grape blister gall is caused by a midge, Cecidomyia sp. This gall may be pink or green and about 1/8 inch in diameter. It occurs on leaves, and a single leaf may contain several galls. The grape tomato gall is caused by several midges, the more common one probably being Lasioptera vitis Osten-Sacken. The tomato gall is a green or red leaf or tendril gall, 1/4-3/4 inch in diameter. The midge Cecidomyia viticola Osten-Sacken is responsible for the formation of the grape tube gall, a conical red or green leaf gall 1/4 inch long.
These gall-forming flies do not often inflict economic injury on grapevines. Removing the galls from the vines mayor may not be of some benefit in reducing the numbers of flies present in a vineyard. Such an action should be taken before small holes are seen in the galls as this indicates that the larvae have already emerged.
Grape tomato galls and larvae.
Current pesticide recommendations may be found HERE