After a female Fly Predator emerges from the host pupa as an adult, she will quickly mate and begin searching for developing flies. When she locates an unparasitized fly pupa, she will eat some of them and lay eggs in others. The eggs hatch inside the host pupa and feed on the fly (killing it in the process) as they grow. How fast the Fly Predators develop depends heavily on temperature. At temperatures above 90°F, development from egg to adult will take a minimum of 14 days. At 70°F this extends to a minimum of 30 days to develop from egg to adult. As winter approaches and temperatures drop, some developing Fly Predators will enter a state called diapause that is similar to hibernation. While in diapause, development halts until temperatures begin to rise again, at which time the developing Fly Predators will complete their development.