Screwworm Flies (Diptera: Calliphoridae): Influence of Sex Ratio on Primiparous Fertility of Caged Populations

The primiparous fertility of caged screwworm flies, Cochliomyia hominivorax , was similar whether the ratios of males to females were 2:1, 1:1, or 1:2. Fivefold sex ratios had adverse effects on fertility except when an excess of females was accompanied by an increase in cage space per fly.