Since Coelomomyces was first described from a mosquito larva (Keilin, 1921, Parasitology 13: 225–34), considerable attention has been focused on the group of fungi as biological control agents of mosquito pests. Despite the intensive investigations that followed, there are still major gaps in our knowledge of the biology and life cycle of the parasite. Attempts to grow the fungus on artificial media have proved unsuccessful. However, it has been possible to carry out the in vivo transmission of a few species of Coelomomyces with varying degrees of success in the laboratory (Madelin, 1968, J. Elisha Mitchell Sci. Soc. 84: 115–24; Couch, 1972, Proc. Nat. Acad. Sci. (U.S.A.) 69: 2043–47; Pillai & Woo, 1973, Hydrobiologia 41: 169–81). In these experiments, healthy larvae of the target species were exposed to a heavy concentration of germinating Coelomomyces sporangia derived from infected mosquito larvae, in a trough containing partly or wholly soil/or water from an infection site.