Thursday, May 31, 2012

Crane Fly

This insect drifted across the driveway as I was waiting for the right butterfly to volunteer itself for the Butterfly House.  Its flight pattern was slow and almost random as it flew, its balance partially controlled by its halteres (see below) until it awkwardly landed on me.  After a brief visit to our refrigerator, it agreed to pose for pictures before it warmed up and flew back into the wild.


This is a crane fly, one of 4250 plus species in the family Tipulidae.  Its leg span was a good 2.5 inches, resembling a mosquito on steroids.  The blunt end of the abdomen suggests it is a male as the female's ovapositor is more pointed, easily mistaken for a stinger.  If you enlarge the picture and look carefully, you can make out thin halteres behind the wings resembling displaced antennae.  They are modifications of the second set of wings which most insects come equipped with.

Knobbed Halteres- Wikimedi
For those like me who were unaware of halteres, they occur in Diptera (flies, mosquitoes and gnats).  They flap rapidly in flight, serving as a type of gyroscope to stabilize the body in flight.  This fascinating mechanism is described further in Wikipedia.
"Halteres thus act as a balancing and guidance system, helping these insects to perform their fast aerobatics.   In addition to providing rapid feedback to the muscles steering the wings, they also play an important role in stabilizing the head during flight."
Compound eye of Crane Fly- Wikimedia
Looking carefully at the picture above, I noticed it had a bright green eye.  You can see a similar bright crane fly compound eye better in the picture from Wikimedia.

Adults for the most part do not feed, flying only to mate and breed.  Their larvae live in moist soil and rotting leaves where they feed on decomposing organic matter, helping in their very small way to build soil.  Some will feed on plant roots and some introduced species are considered lawn pests when  their larvae are present in large numbers.

The next time you see one of these awkward creatures stumbling around in the air or landing awkwardly on you, don't swat it.  Its larvae may some day fatten up your neighborhood Robin.

More pictures at http://www.fcps.edu/islandcreekes/ecology/crane_fly.htm

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