The importance of lipids for queen fecundity and colony growth of Coptotermes formosanus Shiraki was studied. Groups of 100 incipient colonies of C. formosanus were reared on artificial diet containing nine different soy lecithin concentrations. Eggs were counted every 15 d for a 5-mo period at 27 ± 1°C, 93 ± 5% RH, and 0:24 h (L:D) photoperiod. Fecundity per queen was estimated using a developmental rate-based graphic integration technique. At the end of a 1-yr period, the progeny of each colony was counted and recorded. Analysis of variance showed significant differences in queen fecundity and hatched progeny in colonies raised on various diets. Single linear regression analysis showed a small but significant linear increase in queen fecundity and hatched progeny per colony with increasing lecithin concentration. Increase in lecithin concentration explained ≈2, 4, and 8% of the increase in queen fecundity of colonies surviving 6 mo and 1 yr and number of workers and soldiers in 1 yr-old colonies, respectively. This indicates that, although intake of lipids increases queen fecundity and colony growth of C. formosanus, other factors not measured in this study alone or in combination with lecithin play major roles.