"After the initial culture is purchased new flies begin to emerge . A new fruit fly culture will continue to produce fruit flies for 2 weeks or so. Females will lay up to two-hundred eggs in the medium mixture. The eggs will hatch after two days and the larvae will feed on the yeast for seven to twenty days. The larvae will begin to climb up the sides of the vessel to dryer areas to pupate and transform into adult flies in a couple of days. The new flies are ready to mate within two days and have a life expectancy of a little more than two weeks. ""