Studies on Microsporidia Parasitic in Mosquitoes

Stempellia (Thelohania) magna was found to be parasitic in the larvæ of Culex pipiens (Illinois, 1919) and of C. territans (Pennsylvania, 1920). 2. The infection experiment shows that the larvæ become infected by feeding upon the infected larval tissue. 3. The emergence of the sporoplasm of the spore taken into the gut lumen of a new host takes place in the posterior part of the mid-gut from 6 to 40 hours after feeding on the infected material. 4. The schizonts are first noticed in the adipose tissue of the mid-gut and of adjacent tracheæ. 5. The sporogony did not start in the larvæ examined four days after feeding on the infected material. 6. Schizogony is a binary fission of various types. The final form is binucleated. The two nuclei undergo autogamy, forming a sporont. 7. The sporont develops into ordinarily two, frequently one or four and rarely eight sporoblasts; these develop into two, one, four and eight spores.