Leafhopper Newsletter

Adult emergence in Mendocino Co., 2nd-3rd instar nymphs in Lake Co. - June 14

We are now including data for sites in both Mendocino and Lake County.

MENDOCINO COUNTY

In Mendocino County, we are seeing mostly 4th - 5th instars and many newly molted adults. Approximately 98% of the Virginia creeper (VCLH) and 88% of the Western grape leafhopper (WGLH) eggs have emerged.

We project that this week (June 12-18) we will continue to see more 4thand 5th instar nymphs as well as increased adult emergence. Adult populations should continue to grow in the following week (June 19-25) and most of the remaining nymphs will have likely molted.

We are now seeing the start of adult emergence and the ideal period for leafhopper control measures has ended for most vineyards in Mendocino County.

LAKE COUNTY

Leafhopper populations are developing more slowly in Lake County relative to Mendocino County. We are currently seeing 1^st – 4^th instar (stage) VCLH and WGLH nymphs. Although a majority of the nymphs are 2^nd – 3^rd instar, we are still seeing many unknown 1^st instars as well (Fig. 8c). We have not yet observed any newly molted adults.

Now is the time to monitor your vineyard to determine if control measures are warranted.

PARASITOID RELEASE PROGRAM

A batch of Anagrus daanei, the parasitoid that controls VCLH, was released on June 10 in Lake County near Finley.