Catalpa Worm: What Are These Caterpillars Used For?

Catalpa worms or Catawba worms are often mistaken for their identity due to their given name and appearance.

However, these insects are caterpillars which are known to be an ideal bait for channel catfish.

Officially known as the catalpa sphinx (Ceratomia catalpae), these animals are major defoliators of catalpa trees, which are their only host. The larval stage of the catalpa sphinx is called the catalpa worm before it becomes an adult moth, with a heavy body and wide wingspan.

C. catalpae belongs to the family Sphingidae or sphinx moths, which is native to the eastern United States. Their presence can be seen wherever catalpa trees grow, particularly from New Hampshire and Nebraska and south to Florida and Texas.

Local authorities consider catalpa worms as occasional pests since they can defoliate catalpa trees during outbreak years.

However, strict population control on them is not necessary since the caterpillars have a host of natural predators.

What are Catalpa Worms?

The catalpa sphinx was first described by French botanist Jean Baptiste Boisduval in 1875.

Similar to other sphinx moth caterpillars, catalpa worms have a stiff horn near the end of their abdomen, which is relatively elongated and black compared to other species, according to the Pennsylvania State University.

Catawba worms were once found in the state of Maine and across northern New England but may no longer be found in the region.

Regardless, catalpa sphinx caterpillar is expected to follow catalpa trees, which it will remove their leaves over the course of one summer.

However, healthy trees can recover the following year.

To prevent widespread damage, the natural predators of catalpa worms such as wasps and fly parasitoids keep the caterpillars from getting out of control.

The main predator of catalpa worms is the endoparasitoid wasp (Cotesia congregate). These wasps are known for laying their eggs on the back of the catalpa sphinx caterpillar. Once they hatched, they feed on the catalpa worm itself, eventually killing it.

There have been inquiries regarding if catalpa worms are poisonous.

Nevertheless, experts say that their horn is not poisonous at all but this morphological feature is used to scare off the caterpillar's predators.

What are Catalpa Worms Used For?

Aside from being a pest and defoliating catalpa trees, catalpa worms are used for various purposes, including being a fishing bait in the southern US. The caterpillars excrete a strong smell and spread to the water and air, to catch bass, bream, and catfish.

Some fishermen are also known driving far distances or plant small groves of catalpa trees to ensure a supply of catalpa worms.

On the other hand, catalpa worms also benefit the ecosystem since they are a source of food for different animals, in addition to the wasps mentioned earlier.

Recent research on the catalpa sphinx indicate that the caterpillars are not that harmful as previously thought. However, large outbreaks of catalpa worms pose a threat to catalpa trees, which also have medicinal purposes.