ectoparasite

from WordNet (r) 3.0 (2006)

ectoparasite
    n 1: any external parasitic organism (as fleas) [syn:
         {ectoparasite}, {ectozoan}, {ectozoon}, {epizoan},
         {epizoon}]

from The Collaborative International Dictionary of English v.0.48

Ectoparasite \Ec`to*par"a*site\, n. (Zo["o]l.)
   Any parasite which lives on the exterior of animals; --
   opposed to {endoparasite}. -- {Ec`to*par`a*sit"ic}, a.
   [1913 Webster]