The Horsefly & The Worm

The Horsefly is one of the largest flies and is considered to be a pest because of its bite. Its usual food is nectar and plants but the females will drink blood.

There are approximately 3,000 species of horseflies worldwide and some 350 are in North America.

The female horsefly lays eggs, usually near water or soft moist earth. The larvae spends its youth eating small invertebrates or worms.

The horsefly is hairy and has large compound eyes. It uses its vision to detect to movement of its prey.

It is not usually dangerous to humans but can inflict a painful bite, using its long sharp mouth parts in a stabbing motion tearing the skin.




The Catalpa (catawpa) Worm is native to the eastern United States and can be found in the Catalpa Tree.

It takes about 4 weeks for the Catalpa to mature. The eggs are laid by adults in large numbers on the underside of Catalpa leaves and branches. In 5-7 days they hatch. The larval stage is the worm, a caterpillar. They are usually yellow with a black stripe.

The Catalpa Worm easily moves around on the tree, eating leaves, using hook like feet.

In the larval state the worm is easily paralyzed by wasps which lay eggs inside the caterpillar. The wasp larvae feeds eventually killing the worm.


When the time comes to pupate, the worm climbs down to the ground and buries itself where it sheds its skin, revealing pupal skin. The new translucent skin will darken and harden for protection. The Catalpa remain in the ground through the winter in underground chambers. In spring, usually around May, they emerge as an adult Catalpa Sphinx. The brown dull colored moth, also called the Hawks Moth, grows to nearly 4 inches in length.

And the cycle begins again.

We have 2 Catalpa Worm trees in our backyard and each summer we see the worms. In our part of the country, Southern Mississippi, these beauties are frequently used as fishing bait. We don't fish with them so I guess you can say they are protected. They live out their life cycle year after year.

While researching, I learned a lot I didn't know. My husband always said they go back into the ground but I didn't know they emerged as large moths. I also didn't know about the wasps laying eggs inside the worms although there are always lots of them flying around the trees when there are worms present. Poor little helpless caterpillars.

For more information on the Horsefly and Catalpa Worm..click the links below.http://en.wikipedia.org/wiki/Ceratomia_catalpae
http://butterfliesandmoths.org/