Sunday, October 24, 2010

Not a mosquito...

Good news! This is not a giant mosquito! It's a crane fly in the family Tipulidae, one of over 1500 kinds in North America.

The one in the photo is a female. You can tell because her abdomen ends in a point. She has a sharp looking organ there called an ovipositor that looks dangerous but is only used to lay eggs, not to sting. 

Some crane flies have wings that span over two inches. They all have a v-shaped groove on their back. Like most flies, they have paired halteres, club shaped organs that stick out of their sides just behind the wings. Halteres are the vestigial remains of a pair of wings lost over evolutionary time. (Most of the other insect groups have two pairs of wings.) 

Flies are usually so small that you need a magnifying glass to see their halteres, but on big crane flies they are proportionately large. You can see them in these photos. Halteres wave around during flight and act like gyroscopic stabilizers. But halteres don’t help big awkward crane flies go any faster so they are easy prey for birds, frogs, fish, and other insects. 

The next time a crane fly enters your home you can relax. It's not a mosquito. It won’t bite. Phew.

Green Eyes!

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