Boosting Catalpa Worm Populations and Managing Ants

Understanding the Ecology

The black ants on your catalpa tree are not eating the caterpillars (catalpa worms). Instead, a parasitic wasp lays eggs on the caterpillars, killing them. The ants are likely tending aphids or feeding on honeydew.

Increasing Worm Numbers

• Collect egg masses or small caterpillars from a heavily infested tree and transfer them to yours in early spring.
• Accept that wasp parasitism is natural; the only practical control is to bolster the caterpillar population so some survive.

No insecticide is recommended, as it would harm the caterpillars you want to cultivate for fishing bait.