This feeding eventually kills the vines, although it appears to happen quickly because the vines suddenly wilt. Vines must be protected from late June through mid August from egg laying adults and newly hatched larvae with an insecticide application to the base of plants. They can feed in fairly large groups, quickly defoliating plants. Care should be used around these pests since they can excrete a substance called cantharidin that can raise blisters on the skin. There have been many calls about tomatoes that look great but have not set any fruit, the flowers just fall off.
Fruit set is a rather complicated process, dependant on many factors.
Weather, specifically temperature and moisture conditions being of primary importance. If conditions are not right, fruit set will not occur. Plant development and nutrition levels in the soil are also important factors. Cucurbits are also affected by these same factors with the added dimension of having separate male and female flowers. Generally, the first flowers to be produced on cucurbits are male, with more female flowers developing as the season progresses.