Control of the Western Grapeleaf Skeletonizer (Lepidoptera: Zygaenidae), a New Grape Pest in the San Joaquin Valley, California

Harrisina brillians Barnes and McDunnough is native to North America, but it first invaded California near San Diego in 1941. An attempt at eradication was not successful. In 1961, the new pest was found in the San Joaquin Valley, where more than two-thirds of California’s billion-dollar grape industry is located. In spite of other attempts at eradication, it became firmly established by 1975 and has caused severe damage to commercial vineyards, backyard grapes, and native wild grapes. Test chemicals were applied at 1,870 liters/ha by hand sprayer. Kryocide, methomyl, naled, carbaryl, and diflubenzuron were applied at 8.97, 0.79, 0.56, 1.12, and 0.14 to 0.28 kg of AI/ha, respectively, and control was ≥99%. Dipel applied at 1.12 kg of Al/ha was less effective, and two applications may be needed to control a vineyard infestation.