Gallmakers on leaves
Galls are formed by various fly species. Each makes a characteristically shaped gall. Shown are tumid galls. Rufus Isaacs
Many galls of various shapes occur on grapevines as a result of attack by small flies (gall midges). Galls can occur on leaves, tendrils and blossom buds. Numerous species of gall midges attack grape. Galls are formed by larvae of small cecidomyiid flies, which lay their eggs into the leaf. There may be one to three generations per year. The life cycle begins with eggs laid within the unfolding buds or shoot tips. Orange, maggotlike larvae hatch from these eggs and enter the vine tissue. As the larvae feed, galls form around them.