First Eastern Tent Caterpillar Siting (For Me) in Texas

You know, you can probably count me among a small handful of freaky people that would be excited to find colonies of tent caterpillars (I've posted about forest tent caterpillars here). John and I went out to Bastrop a few weekends ago and went hiking at the Colorado River Refuge.

I was very excited to come across an area of the refuge that was supporting a pretty good population of Eastern tent caterpillars, Malacasoma americanum.

Growing up on the East coast, these were a common sight - and considered a pest by most - among the ornamental apple, plum and prunus trees. But I rather like them. They are a fascinating colonial species, not truly eusocial like the ants and bees, but social enough to build a protective shelter.

They also lay little pheromone trails along branches that their colony mates use to find the best patches of new leaves to munch on.

The silken shelter protects these caterpillars from parasitoids, kind of.

Parasitoids are a special class of insect that spend their larval stage as a parasite to another insect. These caterpillars, for example, are host to a number of wasp and fly species. What happens is that the adult female parasitoid finds the caterpillars and lays her eggs inside the caterpillar. The larvae of the parasitoid then grow by eating the caterpillar from the inside out. So, yea. Maggots eating you alive. Kinda gross, but also pretty awesome.

Anyhoo, theory goes that these webby nests protect the caterpillars from the marauding flies and wasps trying to bomb them with their eggs. The caterpillars forage at night to try to escape the parasitoids. The parasitoids obviously make it through the protection on a regular basis, or...they would've gone extinct a long time ago. That's the arms race that is evolution.

Birds can also break through the nests of course, and would be getting themselves quite a tasty treat if so.

There you have it. Eastern tent caterpillars in Bastrop, Texas. Cool!