I had catalpa worms on my trees in June. There is one big 50'+ tall "momma tree" and two smaller volunteers that are about 12' tall next to the pond. I have never seen any worms on the big tree. If they get worms it must be near the top. But the small trees have had worms for the last two years. The worms showed up in late May or early June. All the leaves on the small trees were eaten off by the first week in July. The worms disappeared shortly there after. The trees have since put out new growth.
