Most D. recens females remate within a few days and use the sperm of multiple males to sire their offspring. We found that the proportion of females that produced both wild-type and dark-eyed offspring, indicative of multiple mating, increased with the number of days the flies were held together ( ? 5 2 = 27 , p < 0.0001), and that this was owing to a lower number of multiply mated females in the 1-day treatment (? 2 = 20, p < 0.0001; figure 3; electronic supplementary material, figure S7). Whether the wild-type eyed males in the cage were ST or SR did not affect this pattern ( ? 6 2 = 10 , p = 0.13). Using the occurrence of mixed broods is a conservative estimate of remating rate, as we cannot detect when females mate with males of the same eye colour genotype or mate twice but do not use the sperm of both malesbining SR and ST cages within each day, when flies are kept together for 24 h, 20% of females produced mixed broods, indicating they mated with both dark and wild-type males. This suggests that about 40% of females mated at least twice within 24 h, because we only detected half of the broods produced from double matings (95% CI 0.32–0.47). 66% mated at least twice) and increased to approximately 50% after 3 days, suggesting that all of the females had mated twice (figure 3).