snow fly
noun
variants:
or snow insect
Definition of snow fly
1
: any of several minute insects that constitute a genus (Boreus) of the order Mecoptera and sometimes appear on the snow in great numbers and in the males have vestigial wings but in the female are wingless
2
: any of several small American stone flies (especially Taeniopteryx nivalis or Capnella pygmaea) often seen on snow
3
: snow gnat