Progeny released via the two alternative pathways for emergence display different sex ratios as well as sizes. Among adults who emerge during the summer of the same year, the sex-ratio is biased towards males. Among the "second-generation bees," however, the sex ratio is female biased. Further, spring-emergent adults weigh more than summer-emergent ("second-generation") adults. These differences have been proposed to be attributed to the chances of survival to mating of the two sexes and the metabolic costs involved in development. Bees that undergo diapause and emerge in the spring must endure the long winter, and thus require more food stores. As a result, they will be larger when they mature. Another explanation has been that smaller bees mature faster and thus are able to mate more quickly when they emerge in the summer to avoid the cold, harsh conditions of the winter.