Grape Rootworm, Fidia viticida Walsh (Coleoptera: Chrysomelidae)

Both adults and larvae of the grape rootworm feed on grapevines. Adult beetles feed on the leaves,  and larvae attack the roots of the grape plant.  The activities of the larvae, or grubs, are much more detrimental to grapevines than the feeding of adults.

Adult beetles first begin to emerge from the soil about two weeks after bloom. The adult is grayish-brown, elongate and about 3/8 inch long. By mid- to late June, most of the beetle population has emerged. The beetles chew on the foliage, making chain-like holes in the leaves. Mating occurs and the females lay their eggs under the bark on the vine. Most larvae hatch from the eggs by about mid-July. The small, white grubs drop to the ground and find their way to the roots where they proceed to feed. Most larval feeding occurs during late summer and early fall. The grubs overwinter beneath the soil surface, pupate in the spring and emerge as adults. There is only one generation each year.

If large populations of the grubs build up in a vineyard, vines may be affected adversely. In situations where many or most of the smaller roots of a grapevine are destroyed by larvae of the grape rootworm, the vine may be seriously weakened and its vigor drastically reduced, and death may follow.  Control measures should be directed at the adult as this stage of the insect is the most vulnerable. Look for the beetles and their feeding damage during late June to mid-July.

Current pesticide recommendations may be found HERE

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