Q: We have a twenty-five foot tall catalpa tree that we want to use as shade and not as a source of fish bait. Each year it has thousands of worms that eat all the leaves and leave a nasty mess under it. I was wondering if there is some type control we could use to slow the worms down and save the shade.
A: The easiest way to kill any type of caterpillar is with products that contain Bt, ^Bacillus thuringiensis^ (Green Light Worm Killer, Dipel, Caterpillar Attack, etc). Your biggest problem is how you’ll get the spray up in the tree. If you have good water pressure, use one of the long-necked hose-end sprayers designed for trees. Apply insecticide to the catalpa in late July and repeat every two weeks until late August.
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