The ground is finally covered in a blanket of white, fluffy
snow… it’s a perfect day for a bug walk!
Not surprisingly, there are few insects out in the sub-freezing
temperatures of winter, but a hardy few are specialized to take advantage of
the snowy conditions. Even at
temperatures as low as 20 F, there are still some insects moving about. Their dark bodies contrast with the white
carpet of the forest, making them easy to spot.
On your next snowshoe walk, keep an eye on the snow and you may be lucky
enough to find one of these fascinating creatures:
This tiny creature, commonly called a snow flea, is only
about 4mm long. Despite its name, it is
a springtail, not a flea. This
individual is in the genus Pogonognathellus,
but it is not the only springtail that is commonly active in winter. They are often seen in large numbers at the
base of trees, as if someone sprinkled pepper onto the forest floor. Some theorize that certain springtail species
actually migrate as they jump across snow, taking advantage of this nearly
predator-free habitat to find new food sources.
This insect is often called a “snow fly” (Chionia sp.) since it is most frequently seen walking across the snow. Ironically, this fly cannot fly. In the cold temperatures that it thrives in,
it is difficult to keep wing muscles warm enough to function, so this fly has lost
its wings altogether. It can even be
found mating atop the snow!
Numerous species of spiders can be found crawling on top of
the snow. Some even build webs in the
freezing temperatures to catch other winter-active insects! But no spider will wander too far from an “escape.” Subnivean (under the snow) temperatures are within
a few degrees of freezing throughout the winter; this make the perfect retreat
for when it gets too cold for even the hardiest of insects.
One of the oddest discoveries on a December bug walk near
NBNC was this beetle larva, which was found crawling across the snow. After we posted the image on bugguide, it was
identified by Dr. Margaret Thayer of the Field Museum as a rove beetle (Tachinus sp.). “Odd behavior,” commented Thayer, “we haven't
really heard of them being winter-active.”