Source : Webster's Revised Unabridged Dictionary (1913)

Rubytail \Ru"by*tail`\, n. (Zo["o]l.)
   A European gold wasp ({Chrysis ignita}) which has the under
   side of the abdomen bright red, and the other parts deep
   bluish green with a metallic luster. The larva is parasitic
   in the nests of other wasps and of bees.