What to Know About Catalpa Trees and Their Worms
07.09.2024 - 08:45
/ treehugger.com
Catalpa trees, with two species native to the United States, are known for their beautiful and plentiful blooms and for being the sole source of food for catalpa worms—caterpillars that strip the tree of its foliage and eventually become the catalpa sphinx moth.
Though catalpa worms can completely defoliate a catalpa tree during a single summer, healthy trees typically recover the following year, and natural predators keep the worms from doing too much damage in the long term.
Because the worms are native, they have ample natural predators, including various wasp and fly parasitoids. Worms from the catalpa tree have long been valued as fish bait, and some fishermen plant the trees solely for this purpose. When fully grown, they’re around two-and-a-half to three inches long and somewhat variable in color, though primarily either dark or pale with a black stripe or dots down the middle of the back.
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The endoparasitoid wasp, Cotesia congregata from the Braconidae family, is the primary predator of catalpa worms. These wasps lay eggs along the back of the caterpillar; after the wasps hatch, they feed on the worm itself, eventually killing it. The wasps also inject venom into the caterpillars to control the worm's development. Endoparasitoid wasps benefit the catalpa trees and the ecosystem because they help stop the worms from killing the tree.
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The two species of catalpa tree native to the United States—northern and southern catalpa—have a current distribution from New Hampshire and Nebraska in the northern United States and from Florida to Texas across the South. Historically, the southern catalpa is native from northern Florida to Georgia, and west through