The Collaborative International Dictionary of English v.0.48:

Tettix \Tet"tix\, n. [NL., fr. Gr. ? a kind of grasshopper.]
   1. (Zool.) The cicada. [Obs. or R.]
      [1913 Webster]

   2. (Zool.) A genus of small grasshoppers.
      [1913 Webster]