Several wood-boring beetle species, including the branch and twig borer (Melalgus confertus), can occasionally infest grapevines or cause damage to wine barrels.
Depending on the species, adults are brown to black, cylindrical in shape and 5-10 mm in length. The head is largely hidden under the enlarged pronotum. They have hardened forewings typical of beetles and indistinct body sections. The white cylindrical larvae have enlarged brown-coloured heads.
Adults burrow into the spurs and canes at the base of new shoots to feed, causing them to wilt or break. The pale larvae or grubs burrow through weakened living or dead vine tissues, most often directly above or below a bud. The perfectly round holes that they create are approx. 3 mm in diameter.
Infestations most often occur on weakened or diseased vines. The lead cable borer (Scobia declivis) feeds on grapevines, but the greatest economic damage occurs from the holes that larvae create in wine barrels.
Higher levels of damage occur near wooded and riparian areas that provide alternate hosts.
Control of these pests is best achieved through sanitation and good vine health. Vineyards need to be kept free of wooden debris, and diseased and weakened parts of vines should be removed.
Insecticides applied in spring for cutworm control are likely to also reduce borer damage to some extent.
