The Collaborative International Dictionary of English v.0.48:

Lacewing \Lace"wing`\ (l[=a]s"w[i^]ng`), n. (Zool.)
   Any one of several species of neuropterous insects of the
   genus Chrysopa and allied genera. They have delicate,
   lacelike wings and brilliant eyes. Their larv[ae] are useful
   in destroying aphids. Called also lace-winged fly, and
   goldeneyed fly.
   [1913 Webster]

WordNet (r) 3.0 (2006):

lacewing
    n 1: any of two families of insects with gauzy wings
         (Chrysopidae and Hemerobiidae); larvae feed on insect pests
         such as aphids [syn: lacewing, lacewing fly]