EPOW - Ecology Picture of the Week

Snow Fly (Chionea sp.), Family Tipulidae, Order Diptera

Explanation:  What lives on snow and ice, and also in high-country forests after the thaw?  In a previous EPOW, we discovered one insect (snow scorpionfly) that is part of life on the ice, but here is an even more bizarre species.  This is a snow fly of genus Chionea.  It belongs to the crane fly family (Tipulidae) but ... look closely ... it has no wings.  Why would a crane fly develop with no wings?

The answer is that this is an ancient lineage but a very advanced or specialized form that lost its capacity to fly because flying is unnecessary and would put it in harm's way beyond the local patch of snow or ice.  Also, flying demands high metabolic energy which may be beyond the capacity of an insect living below freezing temperatures.  But I captured this specimen not on ice or show, but instead in a mid-elevation conifer forest in the Cascade Mountains of Washington state during early summer, after snowmelt.  

The genus is generally poorly studied, and this individual likely represents an undescribed species.

Snow flies are bizarre creatures.  Look closely at the following image.  The head and eyes are much reduced in size, seen here on the right side of the photo.  On the tail end is the much-enlarged male reproductive organ.  And there are no wings to be seen anywhere.

Snow flies can be seen walking across snow and ice in winter.  Achieving the adult form during winter may help it avoid summertime predators.  And it is not the only wintertime insect found on snow and ice ... previously, we also explored the snow flea.  

The snow fly can remain active below freezing temperatures (32^oF or 0^oC) probably because of a special enzyme in its blood that resists freezing.  It produces glycerol, a chemical found in antifreeze in your car (ethylene glycol), which makes the blood thicker so that molecules cannot form crystals.  If we could unravel the full blood chemistry of snow flies, perhaps one day we could genetically engineer other life forms to withstand sub-freezing temperatures ... we leave that to your imagination!

The tiny head of a snow fly. 
Note the multi-faceted but tiny eyes.