Q. Some kind of thrip-like bug has invaded my garden. My grapes leaves are brown and drying up from these bugs. There’s tiny black spots where they were. There’s so many of them I can hear them as I approach the plant. I applied Spinosad in September but it didn’t do anything. Now they’ve gotten into my peach tree.
A. The tiny black spots on grape leaves is fecal matter (poop) from leafhoppers, not thrips. Thrips are very common on grapes here that feed on plant juices from the leaves of grapes and other plants.
Leafhoppers start building their colonies in grapes around April. Once established, they will build huge colonies in the grapes and spread to other plants.
|grape leafhopper damage|
They are easy to get under control in April and May when they are young. They are extremely difficult to control without some heavy duty insecticides later in the season.
Spinosad, a natural insecticide spray, works great if applied early in the season such as April and May. Later in the season you will need to bring out some heavy duty artillery to get them under control.
|Leafhoppers greatly magnified. They are maybe 1/8 inch long|
I hate to recommend anything this late in the year because the insecticides needed are very heavy-duty. It is best if you can wait until next spring and begin treatment early with Spinosad or pyrethrin sprays.
|Spinosad active ingredient|
Alternate Spinosad with insecticidal soap and neem oil. Make sure to spray the tops and bottoms of the leaves. If using Spinosad, two sprays about six weeks apart starting in late April will take care of them, the hornworms and the skeletonizers all at the same time.