Wanting Sex But Getting Death

In this, my 200th post, I wanted to take a moment to tell you about something very cool, something a few of you probably never knew existed.

bola spider

In a conversation in class about reproductive isolating mechanisms (factors that can keep populations from interbreeding), the use of pheromones by insects was mentioned. As I’m sure everybody knows, some species of insects use these chemicals to attract mates, sometimes over great distances. For example, some male months can attract females from a mile away with the pheromones they release. Pheromones are also important in certain species as a way to advertise “Hey, baby, I’m your species.” In other words, pheromones can help keep a species cohesive, insuring that it doesn’t mate with the wrong bug.

Much like a homeland security official on a MySpace website, there is a spider which has learned to use these pheromones to lure in a moth, at which point it makes use of an ingenious method to capture it.

Bola spiders (pictured at right) release female moth pheromones and attract male moths. They also produce a glob of sticky glue which hangs on the end of a single thread. When the male moths approach looking for a mate, the spider begins spinning this glob around like a lasso. Upon making contact with the moth, the spider reals in the line to have dinner.

Bola spiders get their name from the cowboys of southern South America (Argentina, Chile, Uruguay), after the bolas they use for hunting. A bola has two balls connected with a rope that they would throw to entangle the feet of an animal. It was used very much like North American cowboys used a lasso.

I found surprising little information on bola spiders online, but as best I gather, there are many species with a worldwide distribution.