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Treebeard's Stumper Answer
24 April 98

Born To Die

The warm weather this week is starting to bring out the insects. We've all been noticing swarms of tiny flies dancing in the air above the lawn, like airborne schools of anchovies. I believe these flies are midges, not mosquitoes. They don't bite. They have reduced mouth parts, and probably don't eat at all. They will live and mate and die within a few days. Many insects live like this, especially near water. I imagine them with tiny "Born To Die" tattoos on their fragile legs. What kind of life is this? How is it possible?

The tiny flies we see hovering over the grass live long lives as worm-like larvae in water or moist soil. Then they emerge as short-lived adults that swarm and mate and soon die. The ungainly Crane Flies live similar lives. They're not really "mosquito hawks" at all. One possible benefit is that the winged adults might colonize a new habitat. We think it's normal to live a relatively short childhood as a step to becoming an adult, but it's just the opposite for these insects. Nature works with many different strategies!

Note: It's interesting that Salmon (and Steelhead Trout to a lesser extent) have a similar life strategy. Salmon live and feed in the ocean for years, but they return to their river of birth to reproduce. Once they enter the river, they stop feeding and move upstream with great single-mindedness to mate, spawn, and die. They use themselves up.

Years ago, we were on the North Umpqua River in Oregon in the fall after the Salmon run. It's a profound experience to be on the river with thousands of dead and dying salmon rotting in the shallows. Do their bodies provide nutrients for the hatchlings? What a feast this must have been for the Condor who lived here not long ago! Our dog Sabrina thought she had died and gone to heaven with so many dead fish to roll in. Days later, she developed "Salmon Fever" (a kind of Salmonella?) and nearly died for real.

Has there ever been a human society in which adults are only tolerated to produce more children? The sci-fi movie Logan's Run suggests such a future. Perhaps we're heading in that direction now, with so much media emphasis on "youth culture".

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