The Collaborative International Dictionary of English v.0.48:

Eruca \E*ru"ca\, n.; pl. Eruc[ae]. [L., a caterpillar, also, a
   sort of colewort.] (Zo["o]l.)
   An insect in the larval state; a caterpillar; a larva.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Eruca
    n 1: annual to perennial herbs of the Mediterranean region [syn:
         Eruca, genus Eruca]