Plan the perfect garden with our interactive tool →

How to Kill Catalpa Worms

Catalpa worms, otherwise known as the Catalpa Sphinx or "Catawba" worms, are the larval stage of the Catalpa moth. Feeding primarily on the vegetation produced by the Catalpa tree, Catalpa worms are capable of stripping the leaves off these trees in only a short amount of time. Favored by anglers since the late 1800's, Catalpa worms are controlled through removal as well as by chemical means. The pesticide carbaryl is widely recommended for control.

Put on gloves before beginning manual removal of Catalpa worms. Locate the worms along the tips of the Catalpa tree. Look for the long slender worms themselves or signs of egg sacks along the ends of branches.

Clip the infested branch ends from the tree with bypass pruners. Attempt to make the cuts at a natural junction point in the limb.

Dispose of the cut trimmings, worms and egg sacks by burning.

Put on a hat, safety glasses, face mask and long sleeve shirt for protection before spraying carbaryl pesticide overhead.

Shake a container of pre-mixed carbaryl pesticide thoroughly before use. Adjust the spray nozzle to a stream and spray limbs where Catalpa worms are seen and cannot be reached or on limbs that you do not want to cut.

Catalpa Worms And Parasitic Wasps

One of the best natural insecticides is one you don’t have to purchase, mix or even apply. Catalpa trees are the sole plant hosts for catalpa caterpillars, commonly called catalpa worms. The female sphinx moth lays eggs in clusters on the undersides of catalpa leaves. When the eggs hatch, the worms that emerge typically have black and yellow bodies and a hornlike structure at the end of their abdomens. Surprisingly, even though the larvae have eaten internal worm tissue, the caterpillar is usually still alive when the cocoons are attached to its back. Braconid wasps are harmless to people because they do not sting.

Garden Guides