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I usually have great grape harvests, but toward the end of the season I get caterpillar and their adult moths that arrive and skeletonize the leaves. Sometimes they seem to arrive earlier and when the leaves are eaten the grapes get too much sun. The moths are about 1 inch and seem to be all black. The caterpillar stage are about 1/2 inch and kind of looks like zebra stripes. I have used BT with fairly good success but it is difficult for me to get out often enough to keep up with those darn caterpillars. I’m hoping to cut them off at the pass, so to speak, and stop them from coming back every year. I’m also wondering if my BT mixture is strong enough. I follow the bottle directions…I think! LOL Thanks!

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2 answers

  1. You may not know it but you wrote the name of the moth that's feeding on your grape leaves when you described what the moth was doing; the moth in question is called the grapeleaf skeletonizer--no kidding! The eggs are laid in clusters on the leaves and the larvae feed on the underside of the leaves.

    For starters, do not hand pick the larvae unless you are wearing thick gloves impervious to thorns: when in the striped stage, the larvae bear long black poisonous spines that cause skin welts. Bt is best applied in the egg stage or the young larvae stage, and two applications is usually needed. Bt is not as effective when caterpillars bear their zebra like stripes, which is the fourth and fifth stage. You might try a fruit tree spray with neem, or a pyrethrum dust. As you know I gear my recommendations towards organic methods/products or the least toxic products, but if you want to bring in the big guns, any insecticide that kills caterpillars or thrips will also work on the grape leaf skeletonizer. Good luck!

    1. In response to Kris_Wetherbee

      Excellent!!

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