The Collaborative International Dictionary of English v.0.48:

Halteres \Hal*te"res\ (h[a^]l*t[=e]"r[=e]z), n. pl. [NL., fr.
   Gr. "alth^res weights used in jumping, fr. "a`llesqai to
   leap.] (Zool.)
   Balancers; the rudimentary hind wings of Diptera.
   [1913 Webster]