Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.
In the report "Females' choice of `good genotypes' as matesis promoted by an insect mating system" (12 Sept., p. 1187),W. B. Watt et al. do not evaluate the fitness of the progenyof Colias butterflies, as suggested in This Week in Science(12 Sept., p. 1131).