Green Oasis

Iain Couzin, a beautiful mind over at Edge, has an explanation for those swarms of Mormon crickets. I’ve run over my share of crickets on the roads of Utah, but Iain has figured out why they all seem to be going across the road in the same direction.

If you look at these swarms, all of the individuals are marching in the same direction, and it looks like cooperative behavior. Perhaps they have come to a collective decision to move from one place to another. We investigated this collective decision, and what really makes this system work in the case of the Mormon cricket is cannibalism.

You think of these as vegetarian insects—they’re crop pests—but each individual tries to eat the other individuals when they run short of protein or salt, and they’re very deprived of these in the natural environment. As soon as they become short of these essential nutrients, they start trying to bite the other individuals, and they have evolved to have really big aggressive jaws and armor plating over themselves, but the one area you can’t defend is the rear end of the individual—it has to defecate, there has to be a hole there—and so they tend to specifically bite the rear end of individuals. It is the sight of others approaching and this biting behavior that causes individuals to move away from those coming towards them. This need to eat other individuals means you are attracted to individuals moving away from you, and so this simple algorithm essentially means the whole swarm starts moving as a collective.

Interesting stuff. At this point, I’m tempted to try to draw a parallel between Mormon cricket behavior and the behavior of Mormons themselves, but I’ll leave that up to you. The analogy would probably apply to me equally well anyway.