Catalpa worms are the larval stage of the catalpa sphinx moth ( _Ceratomia catalpae_ ). These distinctive caterpillars are yellow and black, often with a prominent black stripe and dots, though some may appear paler. They typically grow 5 to 7.5 centimeters (2 to 3 inches) long. Known for feeding on catalpa tree leaves, they are also commonly used by fishermen.
Annual Appearance
Catalpa worms typically emerge from late spring to early summer, often appearing from May through November in some regions. Their exact timing varies by geographical location and weather, with warmer climates seeing earlier emergence. This initial emergence usually lasts two to three weeks.
Multiple generations can occur within a single season, especially in southern areas with warmer temperatures. Some regions see two to three generations annually, while others, like Texas, can have four or five. These subsequent broods mean caterpillars can be present into the fall, with generations sometimes overlapping. Infestations are sporadic, varying yearly and sometimes localized to specific trees.
Understanding Their Life Cycle
The catalpa sphinx moth life cycle begins when adult moths emerge in spring, typically March to May, after overwintering as pupae in the soil. Females deposit 100 to 1,000 yellowish eggs on the undersides of catalpa leaves or branches. These eggs hatch into tiny, pale larvae within five to seven days.
Newly hatched catalpa worms feed gregariously on catalpa leaves. As they grow, they molt several times, becoming darker and larger. After about three weeks, full-grown caterpillars burrow 5 to 7.5 centimeters (2 to 3 inches) into the soil to pupate. New adult moths can emerge in about two weeks during warmer months, or pupae may overwinter, completing the cycle and enabling multiple generations.
Significance and Discovery
Catalpa worms are valued as fishing bait for their effectiveness in attracting various fish species, including catfish, bluegill, and bass. Their tough skin helps them stay on the hook, and they are believed to release an attractive scent when damaged. Some fishermen plant catalpa trees to ensure a consistent supply.
To find catalpa worms, locate catalpa trees, their sole food source. Catalpa trees have large, heart-shaped leaves and may produce long, bean-like seed pods. Signs of feeding, such as defoliated or chewed leaves, indicate their presence. Worms can be picked directly from leaves or dislodged by shaking branches over a tarp. While popular bait, these caterpillars also serve as a food source for birds and other natural predators.