BT (Bacillus Thuringiensis) will control the caterpillars. You can find it at Home Depot or Lowes. The Powdered form is sold under the name DIPEL DUST. I prefer the liquid form because itÂs easier to apply with a sprayer. This stuff only kills caterpillars and some grubs and worms. It will take about three days for them to stop eating and start to die. ItÂs the best option other than picking them off by hand and feeding the birds.

Sevin worked for us. We bought a concentrated bottle at a nursery and sprayed it on with the hose. You have to do a couple of applications though, because the WGLS (Western Grapeleaf Skeletonizer) catepillars will keep coming for a while. Did you see a lot of blue-black flies around your grapes earlier this year? We had tons of them last year and they destroyed our grapes. I wasn't sure if they were going to come back, but they did and are looking great this year. I made sure to keep them high off the ground and keep the bases clean of any debris over the past year, because that is where they lay their eggs. They are nasty and I hope you can get rid of them soon! Good luck.

OK, I pulled all the caterpillars off this morning. I'll keep checking for the next several days as I probably missed a few.

As for the BT... my grapes are a couple of years away from producing any fruit, so I'm not worried about using pesticide right now. My question is, how toxic is the stuff? Is it OK to use when there are grape clusters?

thanks again!

It is harmless to anything other than caterpillars and worms and grubs. It's not a poison. Bacillus thuringiensis (BT)is a bacteria that affects and kills certain target hosts. Bacillus thuringiensis isrealiensis is another bacteria that attacks mosquitos and is the active ingredient in mosquito dunks. It is one of the most beneign ways of dealing with worms and caterpillars on food crops other than hand picking. Just follow the directions.

I had the same problem with my grape vines year before last. BT was the only thing that saved them....I'd been diligent about picking the catties off, but just couldn't keep ahead of them. The vines looked weak the rest of the summer, but made it through.

Mark the date for next year. These things lay eggs every year and you can get around the spraying if you search the plant and pull off the leaves with eggs. I had pretty good success with this method as I use no chemicals in my garden. If you are dilligent about checking during hatching time you can spot damaged leaves early and get rid of the bugs. Good luck.

Not grapes but my passion flower vines have been eaten to bits by stinkin catepillars! At first I thought it was neat, so did my 3 yo. That was when I only had a few, now they have taken over & I barely have any leaves left. So sad!

I assume I can use this stuff too? Don't think it makes a diff, but they are the orange & black cats.

Yes, use the BT on those caterpillars too...or pick them off and squish 'em. :-)

Kevin

Thanks Kevin! Or just let my 3 you son take care of them. ;-p We took a couple to school for show & tell the other day.

They invaded my new grapevines last year & were about 3/4 inches long when I found out, and again this year. Only thing I could do was to cut them in half with cheap scissors. When they're bunched up, I'll cut off whole leaf and make sure I cut each one of them since little ones are usually in a row. Just look for skeleton leaves area and they're always on the shady side of green leaf nearby. Didn't know about BT. I'll try it.

BT works great for them but you have to apply it before they've done most of the damage. I reapply it when it rains or if it's been about 2-3 weeks.

What is bt

It's a powder, you sprinkle it on. Don't remember the full name, it's latin I think. Just google bt for bugs.