Insects in the Vineyard

Foliage Insects

• Japanese beetles are tiny insects with metallic green bodies that damage the leaves of grapevines. Although small infestations only cause aesthetic damage, large infestations cause severe defoliation that results in stunted growth and fruit production. Measuring less than 1/16-inch, aphids are sucking insects that appear in shades of brown, green and black. Leafhoppers are wedge-shaped, yellow insects that measure 1/8-inch. Both types of insects are commonly found on the undersides of foliage where they suck cell juices with their piercing mouth-parts. Infested foliage appears yellow, speckled and discolored along the veins. Grape phylloxera creates tiny galls on the foliage that prevents photosynthesis and causes infested leaves to wilt.

Bud Insects

• Grapevines attract a large number of moth larvae collectively called climbing cutworms that feed on the tissues of buds and young leaves at night, causing them to appear spotted. Adult flea beetles damage the buds as soon as they begin to swell. The insects puncture holes in the buds, causing the insides to appear hollow. The adults and larvae also feed on leaf tissue between the veins, leaving behind a skeletonized mess

Berry Insects

• Native to eastern Asia, the multicolored Asian lady beetle is attracted to grapes previously damaged by birds or wasps. The beetles contaminate the wine because they are difficult to remove from grape clusters and are crushed with the berries. The larvae of grape berry moth tunnel inside green grapes and feed internally. Tiny red spots on the berries indicate the insects' points of entry. Sometimes the larvae also pupate in the fruit clusters where they have fed.

Shoot Insects

• Adult grape flea beetles damage the primary buds on grapevines and prevent them from developing into shoots, thereby affecting the plant's fruit production. Although the larvae of the insects also feed on the leaves, their damage does not affect grape quality. The grape cane gallmaker creates galls on the shoots, directly above the nodes. The reddish-brown galls are larger than the nodes and feature longitudinal scars. Female grape cane girdlers lay eggs inside green shoots and girdle the wood directly above the below the eggs, causing it to break or die.