The Collaborative International Dictionary of English v.0.48:

no-see-um \no-see-um\ n. (Zool.)
   Any of several minute two-winged biting insects of the family
   Ceratopogonidae that suck the blood of mammals and birds
   and other insects; also called biting midge and punkie.

   Syn: punkie, punky, punkey, biting midge.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

biting midge
    n 1: minute two-winged insect that sucks the blood of mammals
         and birds and other insects [syn: punkie, punky,
         punkey, no-see-um, biting midge]