Monday, May 5, 2014

Short Little Lives

My students pulled this little guy out of a small pond on campus tonight:
Damselfly larva (Odonata sp), College of Lake County, Lake Co, IL 5/5/2014

This is a damselfly larva, most likely in the family Coenagrionidae. It's a young one, quite small with no external wing pads present. It may well remain in an immature stage for several months, perhaps even several years, only to spend a few weeks at most as an adult.

This guy follows the same pattern, but even more so:
Hexagenia sp, Van Patten Woods FP,
 Lake Co, IL 6/5/2014

This is Hexagenia, one of the mayflies (order Ephemeroptera). The story, of course, is that they live for only one day. Which is almost true -- as adults, they live for one day or so. But before that one day, they may spend two years as larvae.

There is a strong, natural tendency to interpret other species in human terms -- not surprising, since that's the only background we have to work with. But science has given us a way out, and these guys show why it can matter. It's easy to look at a swarm of mayflies, and think about that one day of life, and forget about those two years as larvae. (Imagine if we spent 70 years as kids, and 2 as adults!) But if we're concerned about damselfly populations, it's crucial that we pay more attention to those years as larvae, since that's where threats to the population are most likely to be operating.

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