Abstract.Among ten species of neotropical malaria vectors the frequency of egg development by virgin females fed both sugar and blood varied from 23% to 100% and was positively correlated with their mean fecundity. The mean volume of male accessory glands of these same species varied more than 10‐fold and was negatively correlated with population‐ or species‐specific incidence of egg development by virgin females. The accessory glands ofAnopheles nuneztovariGabaldon andAnopheles rangeliGabaldon, Cova Garcia&Lopez are much greater in size than those of the other eight species and are believed to contain secretory materials that stimulate egg production following mating. Insemination did not stimulate egg development inAnopheles albimanusWiedemann whose males possess comparatively small accessory g