Biology and life history of a parasitic nematode Heterotylenchus crassirostris sp. n. (Nematoda: Allantonematidae) parasitising Musca crassirostris Stein and Stomyxis calcitrans L. (Diptera: Muscidae) is described. Details of morphology, percentage of infection, seasonal incidence and the damage caused to the host is also given.
