Airdate: Oct 25, 2007
Scientist: Michael May
Dragonflies - Mating Strategy
One of the world's most venerable insects has developed a sucessful means of reproduction.
Dragonflies - Older Than Dinosaurs, Younger Than Springtime
Ambience: river ecosystem
JM: They're one of the world's most ancient creatures - older than dinosaurs. So when it comes to their mating strategy, you've got to think it's pretty effective. I'm Jim Metzner, and this is the Pulse of the Planet. We're sitting on a dock at a pond in Middlesex County, New Jersey, watching dragonflies like the Green Darner and the Eastern Pond Hawk.
MM: "Eastern Pond Hawks -- you see them perched on the boards of the pier. The reason that they're doing that because it's kind of a dull day. They're a little cool, and they're perching on a nice flat reflective surface to get warm. A lot of dragonflies spend a lot of their time actually regulating their body temperature by basking like a lizard might,"
JM: Mike May is an entomologist at Rutgers University.
MM: "The one we're looking at right now is a male and I can tell that because it's all sort of a powdery blue color. Interestingly the females are bright green and black and the males start out that way as well. But as they mature sexually, they also turn color and become powder blue. And that's an indication to other male Eastern Pond Hawks that they are in fact mature rivals and the other male had better stay out of their territory. Most of the larger dragonflies that you see are males that are waiting for or searching for females, because the females have to come to water to reproduce. The immatures develop in water. And so the males come to the waterside waiting for females to show up and then they'll grab the female and they'll mate."
JM: We'll hear more on dragonflies in future programs. Pulse of the Planet is made possible by the National Science Foundation. I'm Jim Metzner.