The developmental period for the parasitic stage of Romanomermis culicivorax in Culex pipiens was determined at constant and fluctuating temperatures. The median developmental times at 15, 18, 20, 27, and 32 C were 27.6, 17.2, 11.5, 7.1, and 5.8 days, respectively. The optimum temperature range for development of the parasitic stage in C. pipiens was 20 to 32 C. The threshold for development wa...