The Collaborative International Dictionary of English v.0.48:

Locusta \Lo*cus"ta\, n. [NL.: cf. locuste.] (Bot.)
   The spikelet or flower cluster of grasses. --Gray.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Locusta
    n 1: a genus of Acrididae [syn: Locusta, genus Locusta]