The process of sexual maturation was studied in the ant Iridomyrmex humilis. Spermatogenesis starts during the pupal stage and sperm is transferred to the seminal vesicles during the first four days after emergence. The testes start to degenerate early in the pupal stage and totally shrivel up during the first days after emergence. Males therefore have a fixed amount of sperm. Both males and females reach sexual maturity only 2-3 days after emergence; some of them mate as early as the first day after emergence. Overall, it appears that the length of time needed to reach sexual maturity in ants is highly correlated with the mode of colony founding. The maturation period is much longer in those species in which young queens initiate colonies without the help of workers (independent founding) than in those where young queens need the help of workers (dependent founding). This is probably associated with the fact that independent founding queens require large amounts of energy reserves in order to found colonies, these energy reserves are accumulated after emergence. In contrast, dependent founding queens do not accumulate as many energy reserves and are therefore sexually receptive at a younger age.