Larval form of the Ceratomia catalpae moth
Catalpa (catawba) trees are essential to the life cycle of the large, brown, night-flying moth Ceratomia catalpae. The United States has two species of catalpas -- southern catalpa (Catalpa bignonioides) and northern catalpa (Catalpa speciosa). The Ceratomia catalpae (catalpa sphinx moth) can use either tree as a host, and catalpa moths may be found wherever catalpa trees grow.
The female moths lay piles of tiny, translucent, pearl-like eggs on the undersides of catalpa leaves or on the branches, often several hundred or even a thousand at a time. When the eggs hatch, tiny larvae emerge.
As the larvae feed on the catalpa leaves, they grow through several stages of development, becoming darker in color as they grow older. At their largest, they can measure up to three inches long. The catalpa worms always have a "horn" -- a spike at the end of their abdomen -- like the tobacco and tomato hornworms.
Catalpa worms spend their time eating catalpa leaves, and when a catalpa tree has hundreds of larvae consuming its foliage, it often develops areas of defoliation that give the tree a ragged appearance. Fortunately, the tree usually tolerates the abuse without long-lasting ill-effect.
to pupate. The life cycle is complete when the large adult sphinx moths emerge, mate, and lay more eggs. Two or three lifecycles in a growing season are common.
Catalpa worms are said to be excellent fish bait for catching bluegill and catfish. One method is to cut the worm in half and turn it inside out (using a match) so the flavor is released to attract the fish. They can also be cut into pieces and threaded on a hook like earthworms. The skin of the worm is tough, so it stays on the hook and the worms are said to be lively for long periods of time. (Bait durability is much appreciated by fishermen.)
Worms can be shaken out of a catalpa tree onto a tarp spread on the ground. Fishermen sometimes preserve the worms for future fishing expeditions by packing them in cornmeal or sawdust inside glass jars or shoe boxes and freezing them. When they are thawed, the worms are still fresh and alive -- or if not, catfish like dead catawba worms, too.
The catalpa tree in the image below grows in the town of Van Buren, Missouri, about 150 yards above the Current River. It is the largest catalpa tree I've ever seen. Catalpa trees can grow 70 or 80 feet tall, and this tree is all of that or more. It would be difficult to shake it for worms.
All this writing about fish bait makes me feel like going fishing! I even know where there's a catalpa tree in our neighborhood.
Image credits: Ceratomia catalpae adult photo (found on Wikipedia) taken by Shawn Hanrahan at the Texas A&M University Insect Collection in College Station, Texas. Catalpa worm photo (found on Wikipedia) taken by contributor Taxidermistjake.