The Trichostrongyles compose a group of bursate nematode parasites that have reduced buccal capsules and which inhabit the stomach oar small intestine of all types of vertebrates. The trichostrongyles compose the superfamily of parasitic nematodes with the largest number of genera and species, but the cat is only host to two members of this genus and both are within the same family the Molineidae which has representative parasitic in bats, primates, rodents, lagomorphs, and ruminants. The two genera that occur in the domestic cat are Ollulanus and Molineus. Ollulanus is characterized by being ovoviviparous and having a female tail ending with several tubercles. Molineus contains oviparous females that have a tail terminating in a single caudal spine.