Compositions suitable for topical use to treat ectoparasite infestations are described. The compositions are suitable for use on the hair of humans or animals, without the need for pharmaceuticals or medicaments. The compositions are essentially nonaqueous and non-Newtonian, such that the compositions can be controllably delivered either manually or through use of a dispensing means. One such exemplary dispenser/applicator is described. Although the compositions are otherwise substantially free of water, they exhibit good risibility characteristics and pseudoplastic rheology. Methods for the use of the nonaqueous compositions and kits containing the compositions are also presented.