An important insect pest that deserves special attention is the grape root borer. It is very difficult to control and can destroy entire vineyards. The adult grape root borer is a moth that resembles a wasp. From July through October it can be found flying and laying eggs on grape leaves. Larvae drop from eggs down to the soil where they begin feeding on the small feeder roots, and eventually move into the crown of the grapevine during its two-year larval stage.
Infested vines lose vigor and usually die.
Larvae pupate just below the soil surface and adults emerge from the soil directly beneath the grapevine from July through October. Cultural control measures include mounding soil directly beneath the vines in late June or very early July to prevent adult emergence. These materials are porous and will allow water penetration, but the weave is too tight for adults to pass through. While these cultural controls can eliminate the adults, they offer no control of moths flying into the vineyard and laying eggs on the leaves. The larvae may be able to reach the roots through the landscape fabric.