The temporal abundance and percent insemination of newly-emerged adult female Psorophora columbiae were investigated in riceland sites near Anahuac, TX. Pre- and postmating nights were characterized by low numbers of females and little mating activity (no significant increase in percent insemination) occurring in the study site. Mating nights were characterized by high female abundance in the study site before sunset then steadily decreased until a stable, low level of abundance was reached approximately 2 to 2.5 hr after sunset. On mating nights, percent insemination of female mosquitoes in the study site remained low until sunset, after which it steadily increased until a maximum was reached about 2 hr after sunset. On each mating night, approximately 2 to 2.5 hr after sunset, a mass exodus from the site by primarily mated females with some males was observed.