Nov 28, 2009

Let us now praise crane flies

The humble crane fly comes in many sizes, with hundreds of species in the Southern Appalachians, but there is little superlative about them. They are leggy creatures, and the largest can span about three inches. These are often called "mosquito hawks" under the mistaken notion that they hunt mosquitoes. While they resemble mosquitoes, they are entirely harmless to people and to pretty much everything.
They are the living embodiment of harmlessness, spending most of their life as a worm-like larva that eats muck and goo. Many are aquatic during their larval stage, but anywhere there is moisture and detritus there is probably a crane fly larva turning the mud and slime into something more useful: food for dragonflies, salamanders, fish, birds and all the things that eat crane flies.
Their primary defense is being inconspicuous, whether oozing through mud or in flight as adults. They are slow and quiet fliers, never buzzing like a mosquito, and their long legs afford protection. Often the tip of a leg will make first contact with a spider web, allowing them to fly away before becoming entangled. Some are so sensitive and delicate they use spider silk as a perch, hanging from strands unnoticed by the spider. Others perch on rootlets or hang on the shady side of a leaf. When they find a perch they will hang still and wait for other crane flies to find them. Any damp, shady spot might host a cluster of crane flies.
Should they get attacked, they often lose only a leg. I've seen them soldiering on with as few as three legs. As adults their goal is to mate and deposit eggs where their larvae can thrive, but eventually crane flies will be eaten.
There is a whole family, Trichoceridae or winter crane flies, that emerge during winter months. Five species occur in our area. They can freeze and will become active whenever the sun warms them. You can find congregations dancing in a sunbeam on winter afternoons. They are one of the reasons phoebes and bluebirds overwinter with us rather than retreating to warmer climes.

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