Life history, gonad state, and changes in functional sex ratio in the salt-marsh waterboatman, Trichocorixa verticalis (Fieber) (Heteroptera: Corixidae)

The life history and sexual development of Trichocorixa verticalis were studied in salt-marsh pools in New Brunswick, Canada. Trichocorixa verticalis overwinters as an egg and the adults of the first summer generation appear in late June. The second summer generation appears as first-instar nymphs in mid-July. Males and females mature sexually about 1 month after eclosion, the first sexually mature females appearing 1 week before males. For most of the season, the numerical sex ratio is male-biased. The functional sex ratio (ratio of sexually mature males and females) is even more strongly male-biased. These results indicate that mate competition among males may be more severe than was initially apparent.