alderfly

from WordNet (r) 3.0 (2006)

alderfly
    n 1: dark-colored insect having predaceous aquatic larvae [syn:
         {alderfly}, {alder fly}, {Sialis lutaria}]

from The Collaborative International Dictionary of English v.0.48

alderfly \al"der*fly`\, Alder fly \Al"der fly\
   1. Any of numerous dark-colored neuropterous insects of the
      genus {Sialis} or allied genera. They have predaceous
      aquatic larv[ae], which are used for bait.
      [Webster 1913 Suppl.]

   2. (Angling) An artificial fly with brown mottled wings, body
      of peacock harl, and black legs.
      [Webster 1913 Suppl.]