Leafhopper Newsletter

Egg and nymph densities have declined, remaining adults will overwinter in the vineyard - Oct. 6

MENDOCINO AND LAKE COUNTY

Densities of both VCLH and WGLH eggs and/or nymphs have declined at most sites while adult populations remain relatively elevated at some sites, and may even increase as remaining nymphs molt into adults. The leafhopper adults present at this time are most likely in reproductive diapause and will overwinter in the vineyard.

SUMMARY OF 2016 MONITORING AND PARASITOID RELEASE PROGRAM

This year overall leafhopper populations were relatively higher in Mendocino County than in Lake County. Early season insecticide applications for VCLH did appear to reduce densities, but later in the season VCLH populations increased again at most of these sites, this time with overlapping life stages (adults, eggs, and nymphs all present at the same time). A total of 15,342 Anagrus daanei (the parasitoid that attacks VCLH eggs) were released across 9 sites between April 23 and September 2. While these releases led to increased parasitism at 4 of the 9 sites, in most cases VCLH densities were still very high at the end of the season. See newsletter for further details and summary.