Crops Affected: Grapes

States Affected: CA, AZ, NM, NV, UT, CO, TX, OK, KS, NE, SD, ND, AR, MO, IA, MN, WI, IL, IN, MI, OH, PA, NY, NJ, DE, CT, RI, MA, VT, NH, ME, WV, MD, VA, KY, TN, NC, SC, GA, FL, LA, MS, AL

Life Cycle: Adult emergence and egg-laying take place after the spring flush of shoots and leaves. Adult moths may be active during both day and night. Eggs laid in masses ranging from ten to over 200. Nearly all eggs are laid on the underside of leaves, with the first generation mainly on inner mature leaves under the canopy and subsequent generations on leaves of outer shoots. Larvae feed in groups, side by side in a row, a unique behavior among grape foliage's lepidopterous insects. As larvae mature within a colony, they tend to disperse as isolated individuals or in small groups. Pupae are found in silken cases under bark or in trash around the plant base, with overwintering occurring in the pupal stage. There are two to three generations per year, averaging 67 days from egg to egg.

Damage: Infestations can significantly impact crop yield and quality. At the onset, WGS infestations exhibit initial symptoms of brown, necrotic, and skeletonized leaf tissue due to young larvae partially consuming leaf layers. As the larvae mature, they feed on the entire leaf, leaving only major veins. If left untreated, second and third generation larvae can lead to complete defoliation of vineyards.

Season to Trap: March to June

How To Use: Hang trap with lure inside at shoulder height near at risk or affected crops. Replace lures every 30 days through the season, and replace traps when 70% saturated. Adult males are attracted to the pheromones in the lure and the color of the traps in this kit. Once they land on the sticky trap, they become ensnared, never to mate or lay eggs again.

Additional IPM Solutions: Avoid practices that destroy or disrupt native beneficial insects. Bacillus thuringiensis, or B.t., may be used when larvae are present. Hand-picking larvae is another option, but should be exercised with caution, as the bristles on the caterpillars can cause skin irritation if you touch them.