In the decades since it invaded the US, much has been learned about the Medfly's biology. The following paper is from Science, August 1998, and deals with the impact of ecological factors on the fly's life history.
Medflies stay in waiting mode when they are fed only sugar.
Medflies stay in waiting mode when they are fed only sugar. When fed protein, a scarce resource in the wild, medflies switch to reproductive mode. Medflies that switch from waiting to reproductive mode survive longer than medflies kept in either mode exclusively. An understanding of the physiological shift that occurs between the waiting and reproductive modes may yield information about the fundamental processes that determine longevity. We hypothesized that fruit flies may also be able to enter a waiting mode and that they can live to and reproduce at extreme ages when subject to a lack of dietary protein.