The Purdue Plant and Pest Diagnostic Laboratory

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October 12, 2009

Crane Fly - A Love Child?

Tim Gibb, Insect Diagnostician, Department of Entomology, Purdue University

Some have suggested that crane flies are the result of a mosquito falling in love with a daddy long leg spider.  Interesting love story but until I acquire scientific evidence such as from grocery store tabloids or clear images directly from Photoshop depicting mosquitoes mating with spiders, I am relegating this story to pure fiction.

The truth is that these common flies are just that … flies.  They form their own family called Tipulidae and there are many species involved. As a group they are known for their long slender legs.  The name crane fly, undoubtedly originates from these legs.  Cranes (the bird variety) can wade in very deep water because of their unusually long legs, very tall cranes (the machines) stand on long slender legs way above the structures they help build, and cranes (the flies) also have very thin but unusually long legs. 

Crane flies do have the general appearance of a mosquito but they are much larger and most importantly, they do not bite people.  They may have legs that stretch a full 2 inches or more in length and have wings to match. 

Crane flies live in fairly moist areas where their larvae use a unique siphoning tube in a snorkel-like fashion to poke above the water and take in air. They often occur in plugged roof or tile gutters and in areas that retain water and decaying leaves or other organic matter.  In wet years, we see more crane flies than during dry years.

Some introduced species have become pests in eastern states in wet lawns where they occur in masses by the thousands and actually do damage to the grass. Otherwise, the crane fly is pretty much just a curiosity.  They do not harm people or plants but simply mind their own business.  They do not require controls because they are not considered a pest.

I will keep my eye on daddy long leg spiders, however, just in case there actually is some mischief going on.


Links for more info:

Yard and Garden News - University of MN

Beneficial Insects in the Garden

Crane Flies - University of KY


Click image to enlarge

Crane fly

Crane fly with ruler

Images courtesy of Steve Mayer, Horticulture Educator, Marion Co

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service