is amitraz alternatively one of the active ingredients may be a macrocyclic lactone while the other active ingredient is levamisole or fluazuron many combinations will be appreciated by those skilled in the art of formulating active ingredients for veterinary and pharmaceutical applications thus applicants envision that any combination of active ingredients that has been recalcitrant to co formulation may be more effectively and simultaneously applied as separate formulations using the system of the instant disclosure in a particular embodiment of the method the simultaneous administration of fipronil and amitraz has a stronger or synergistic pesticidal effect as compared to a separate administration of fipronil and amitraz in another embodiment the stronger effect is extended duration of efficacy against acarids more rapid killing efficacy against acarids reduced development of pesticide resistance or any combination thereof unless the context clearly requires otherwise throughout the description and the claims the words u201c comprise u201d u201c comprising u201d and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense that is to say in the sense of u201c including but not limited to u201d by u201c animal u201d is intended mammals birds and the like animal or host as used herein includes mammals and human the animal may be selected from the group consisting of equine e g horse canine e g dogs wolves foxes coyotes jackals feline e g lions tigers domestic cats.