Source : Webster's Revised Unabridged Dictionary (1913)

Chalcid fly \Chal"cid fly`\ [From Gr. chalko`s copper; in
   allusion to its metallic colors.] (Zo["o]l.)
   One of a numerous family of hymenopterous insects
   ({Chalcidid[ae]}. Many are gallflies, others are parasitic on
   insects.

Source : WordNet®

chalcid fly
     n : any of various tiny insects whose larvae are parasites on
         eggs and larvae of other insects; many are beneficial in
         destroying injurious insects [syn: {chalcidfly}, {chalcid},
          {chalcid wasp}]