A. That black wasp-like insect was actually a moth and does not sting. But she will be laying eggs on the undersides of grape leaves. These eggs hatch in a few days and the larvae that emerge will begin to consume the leaf from the underside, often times in a row, leaving the leaf veins behind. For this reason we call them grapeleaf skeletonizers.
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| Great picture of skeletonizer eggs and larvae hatching on the leaf underside from reader. |
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| Also very good picture of adult by reader |
Be careful of these larvae. If they land on your skin
they will “burn” and give you a lot of pain. Use Bt sprays such as Dipel,
Thuricide or Spinosad spray will also work. The sprays MUST be directed toward
the undersides of the leaves as well as the tops. So plan on two passes over
your grape vines; the first time on the underneath side and the second one over
the top.
Spray the leaves enough to give the leaf surface a light
coating on both sides. It does not have to be sprayed until the leaves are dripping
wet. If you have a spreader/sticker to add to your spray then all the better
and it will give you better and longer lasting control.
Both sprays will also control the hornworm which can
consume leaves voraciously.
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| Leafhopper feeding damage to grape leaves. You will also see tiny black specks left behind (poop). These are tiny bugs that hop like a very tiny grasshopper but usually in the thousands on leaves. |
The first plan of attack should be to just remove the egg bearing leaf (or cut off a portion of the leaf with scissors if young plant with few leaves). New grape vines must be protected or they can be stripped of leaves and die. Established vines can take it, so allowing some predation is not particularly harmful. You can get 4-5 generations (amplification) produced in the summer. So early surveillance and intervention prevents the marching army down the road. While these skeletinizers have few predators be cognizant of the fact that predatory wasps will lay eggs on them (I think you will spot paralyzed larvae arched up similar to spinosad or BTK application) and virus infections (liquified remains). I usually leave these alone or move the leaf down into the underlying debris.
ReplyDeleteI brushed up against a leaf that had a lot of worms it burned so bad. Like an acid type of burn. It welter up pretty bad and I’m on my second week with itching.
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