In particular this invention provides for spot-on compositions for the treatment orprophylaxis of parasite infestations in mammals or birds which comprise: (1)a composition comprising (A) an effective amount of a 1-ρhenylpyrazole derivative；and (B) an effective amount of emamectin, latidectin or lepimectin； (2) an acceptableliquid carrier vehicle； and (3) optionally, a crystallization inhibitor. Theinvention also provides for a method of treating parasitic infestations or forthe prophylaxis of parasite infestations in mammals or birds which comprises topicallyapplying to said mammal treating parasitic infestations or for the prophylaxisof parasite infestations in mammals or birds which comprises topically applyingto said mammal or bird an effective amount of a composition according to the presentinvention.
