Scientists were shocked recently to find that two different species of very destructive termites are mating in the wild. Formosan subterranean termites are mating with Asian subterranean termites in South Florida. Currently these hybrid colonies are only in South Florida, because while Formosan termites have spread to 11 states, Asian termites have invaded more recently, and so far are only in Hawaii and parts of South Florida.

The scientists have also discovered that the resulting colonies appear to be even more destructive than their parents, primarily because some of these “hybrid” colonies are growing in size twice as fast as their parent colonies.

“Hybrid vigor” is well known, because it happens sometimes when two plant varieties combine. Hybrid vigor means that the resulting offspring are in some ways superior to either variety. Unfortunately, that is what is happening with the termites—the colonies become larger, faster. With animals, two species normally can’t produce fertile offspring. (For example, the mule, a cross between a donkey and a horse, is sterile.) It is still not known if these hybrid termite colonies will be able to reproduce.

But even if a colony can’t reproduce itself, the sheer numbers of termites in a hybrid colony can be incredibly destructive. It is expected that these hybrid colonies will contain a million termites after five years or so—that’s a very short time to grow so large. It is a case of “hybrid vigor’ at its worst.