The Catawba worm is the larva of the sphinx moth. This black and yellow caterpillar infests the catalpa tree and feeds off of the tree leaves. It is considered a pest mainly because the catalpa tree is popular for it’s magnificent wood that is used for fine cabinetry. The catalpa tree belongs to the family Bignoniceae. It is classified as Catalpa bignonioides.
“Catalpa Tree” is the common name of a tree of the bignonia family. The species is cultivated as an ornamental shade tree, growing to up to 40 feet tall (12 m). Native to the United States, the catalpa tree has silver-gray bark, widely spread branches, and large, pale-green, heart-shaped leaves. The catalpa tree flowers are white, tinged, and dotted with violet or purple. Long, beanlike pods called “Indian beans,” that sometimes hang on the limbs all winter, succeed them. The seeds are winged. Catalpa wood, even in its rawest form, is light and fine and useful in cabinetwork.
Also called “Catalpa” worms, the Catawba worm has both friends and enemies. Lovers of the catalpa tree may employ several methods to destroy these “pests” while fishermen will plant catalpa trees specifically to attract Catawba worms. Fishermen prize these worms as fish bait due to their tough skin and juicy bodies. Catawba worms can even be frozen for fish bait and used at a later time. The Catawba worm is considered excellent bait for catfish. In addition to their usefulness to fishermen, Catawba worms are prized for their attractiveness in many places across the U.S., such as Georgia. While some larvae are black with yellow stripes running down the sides, others are white with black splotches. Catawba worms also have a major distinctive feature – it’s tail. The Catawba worm has a tail-like horn on its rear end.
Catalpa tree lovers prefer to avoid an infestation at any cost or extinguish it, but it is believed that while the Catawba worm can defoliate the catalpa tree up to three times each summer, there appears to be no major consequences to the tree.
An infested catalpa tree can have hundreds, if not thousands of larvae. In fact, if one were to stand under a catalpa tree filled with Catawba worms, it would be like standing in a drizzling rain, except the “rain” would be a steady drizzle of falling frass or rather, caterpillar poop.
Once the Catawba worm has fed to capacity, it drops from the tree and pupates in the soil below. The following spring, the Catawba worm will emerge as a hummingbird moth — the catalpa sphinx moth. The moth isn’t quite as colorful or unique as the larva. They are dull gray and nocturnal, so chances are you will never actually see one.
If you are convinced that the Catawba worm is ruining your catalpa tree, there are several ways to get rid of them. Preventative measures include insecticides such as Ortho Grub-B-Gon Max, Merit, Arena, Mach2, and Season-Long Grub Control. Bacillus thuringiensis (Bt) is also effective. Bt is a live microorganism that kills certain insects. It is used to kill unwelcome insects in forests, agriculture, and urban areas. Bt and other insecticides may be purchased online or at a variety of home and garden retailers.