Abstract: The present invention is directed to a bioassay system for retaining hematophagous arthropods, such as, but not limited to, fleas, ticks and flies, in a microenvironment which mimics the natural conditions of unconfined hematophagous arthropods feeding on an animal. The bioassay system of the present invention comprises a container and an attachment means capable of maintaining hematophagous arthropods under conditions such that the fecundity of the retained hematophagous arthropods is substantially equivalent to the fecundity of unconfined hematophagous arthropods. The container is attached to an animal by an attachment means capable of immobilizing the container to the animal in such a manner that hematophagous arthropods can feed undisturbed from the animal through the container. In one embodiment, hematophagous arthropods are retained in a container comprising a retaining means penetrable by the mouth parts of hematophagous arthropods and a gas exchange means.