Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Temporal variation in the sex ratio of populations with continuous generations is poorly understood. We report changes in the sex ratio of a tropical gall-inducing braconid wasp throughout the fruiting season of its host plant. At the beginning of the season, fruits produce male biased sex ratios; at the end, female biased sex ratios. This change results from differential sex allocation rather than just earlier male emergence. A male bias followed by female bias is predicted following an increase in recruitment as occurs during the start of the main fruiting season, because males are likely to have the more consistent reproductive value over time. An initial male bias might also result from selection for protandry, or from constrained sex allocation during the low-density non-fruiting season.272257267Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)