In particular this invention provides for spot-on compositions for the treatment or prophylaxis of parasite infestations in mammals or birds which comprise: (1) a composition comprising (A) an effective amount of a 1-phenylpyrazole derivative; and (B) an effective amount of emamectin; (2) an acceptable liquid carrier vehicle; and (3) optionally, a crystallization inhibitor. The invention also provides for a method of treating parasitic infestations or for the prophylaxis of parasite infestations in mammals or birds which comprises topically applying to said mammal treating parasitic infestations or for the prophylaxis of parasite infestations in mammals or birds which comprises topically applying to said mammal or bird an effective amount of a composition according to the present invention.