We examined previous reports of Lema praeusta (Fab.) (Coleoptera: Chrysomelidae) as a minor pest of turmeric, eggplant, bottle gourd and pumpkin leaves, but no feeding damage by larvae and adults of L. praeusta were recorded by us on these leaves. We observed feeding by the larvae and adults of L. praeusta on ten species of Commelinaceae plants in no-choice tests. The biology, fecundity and life table parameters of L. praeusta on two Commelinaceae weeds, Commelina benghalensis L. and Murdannia nudiflora (L.) Brenan were determined under laboratory conditions (27 ± 1°C, 65 ± 5% RH and 12L:12D). Total larval development times of L. praeusta were 6.36 ± 0.07 and 7.28 ± 0.11 days (mean ± SE) on C. benghalensis and M. nudiflora, respectively. Adult females lived 106.25 ± 1.17 and 77.65 ± 0.91 days (mean ± SE) on C. benghalensis and M. nudiflora, respectively. Each female laid 272.95 ± 2.39 and 224 ± 1.74 eggs (mean ± SE) during a lifetime on C. benghalensis and M. nudiflora, respectively. The net reproductive rate (Ro), intrinsic rate of increase (rm), generation time (Tc), doubling time (DT) and finite rate of increase (λ) were 136.48, 0.14, 36.17, 5.10 and 1.41 on C. benghalensis, respectively, whereas Ro, rm, Tc, DT and λ were 112, 0.20, 23.64, 3.47 and 1.51 on M. nudiflora, respectively, suggesting that L. praeusta could be a potential biocontrol agent against C. benghalensis and M. nudiflora in the fields of rice, maize, sorghum, soybean, mung bean, peanut and cotton.