The Catalpa worm, often referred to as the Catawba worm, is the larval stage of the Catalpa Sphinx moth (Ceratomia catalpae). This caterpillar is native to the eastern United States and is instantly recognizable due to its exclusive association with the Catalpa tree. While they are notorious defoliators of their host plant, their high value for human use prompts many people to seek them out and handle them.
The Direct Answer: Are They Toxic?
The definitive answer is that the Catalpa worm is not poisonous or venomous to humans or common household pets. A creature is venomous if it injects a toxin, such as through a sting, and poisonous if it releases a toxin when ingested or absorbed. The Catalpa worm does not possess any venom-injecting apparatus.
The stiff, black spike found on the rear end of the caterpillar, which classifies it as a hornworm, is purely a defensive display structure and is completely harmless. When severely disturbed, the caterpillar may regurgitate a pungent, greenish fluid, but this substance is not a true poison and is not harmful to the skin. General handling is safe, and rare accounts of irritation are more likely due to a mild, localized allergic reaction rather than any inherent toxin.
Identifying the Catalpa Worm
The Catalpa worm is the only sphinx moth larva that feeds exclusively on the leaves of the Catalpa tree, making the tree the most reliable identifier. Mature caterpillars can reach up to three inches before they enter the pupal stage.
Their coloration is highly variable, ranging from pale greenish-yellow to nearly black. Most individuals feature a prominent black stripe down the back and a broad yellow or pale stripe along the side. All Catalpa worms share the characteristic stiff, black horn protruding from the posterior abdominal segment, a feature common to true hornworms.
Why People Interact with Them
The primary reason for interaction with the Catalpa worm is its status as a premier fishing bait, particularly in the southern United States. These caterpillars are exceptionally effective for catching a variety of freshwater fish, including largemouth bass, bream, and especially channel catfish. Their effectiveness is linked to the strong scent and internal juices released when they are hooked. Fishermen often plant Catalpa trees specifically to ensure a reliable supply. To keep the bait available outside of the seasonal appearance, individuals harvest and preserve the worms, commonly by freezing them with cornmeal or by purchasing commercially preserved versions.