The functional response of the indigenous green lacewing Chrysoperla nipponensis (Okamoto) and the imported green lacewing Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) feeding on seven different densities of the cotton aphid Aphis gossypii (Glover) (Homoptera: Aphididae) was studied under laboratory conditions at 20°C. C. nipponensis and C. carnea have shown a Type II functional response based on logistic regression analysis. The maximum number of prey eaten by C. carnea was higher than C. nipponensis. Handling time decreased at 24 h for both species, but was higher for C. nipponensis at 12 and 24 h than for C. carnea. The attack coefficient of C. nipponensis was slightly higher than C. carnea in second and third instars. These results indicate that C. carnea may eat more aphids at high prey densities; however, C. nipponensis could be considered a prospective candidate for use as a commercial biological control agent for aphids in Japan. C. nipponensis will become more important than C. carnea from the viewpoint of environmental safety because it is a native species adapted to the Japanese environment, and nontarget effects can be avoided.