Survivorship, developmental rate, fecundity, intrinsic rate of increase, and feeding behavior of the rice green leafhopper, Nephotettix virescens Distant, were studied on 6 rice cultivars and 2 graminaceous weed species, Leersia hexandra Swartz and Zizania latifolia Turcz. N. virescens survived on all 6 rice cultivars, but differences existed among cultivars. N. virescens did not survive on the 2 weed species. N. virescens ingested phloem sap from the 6 rice cultivars but did not ingest phloem sap from the 2 weed species, suggesting that failure of N. virescens to survive on the weeds may be caused by an inability to ingest from the phloem of these plants. L. hexandra and the rice cultivar Nihonbare then were selected as an unsuitable and suitable host, respectively, for further comparisons. Water soluble extracts from Nihonbare and L. hexandra were fractionated into acidic, basic, neutral, and amphoteric fractions. N. virescens then were fed artificial diets of 2% sucrose, or 2% sucrose plus 1 of the extract fractions, or 2% sucrose plus the unfractionated water extract of each plant. Extracts–fractions from Nihonbare had little, if any, effect on N. virescens survival, whereas the water-soluble extract of L. hexandra and its basic, acidic, and neutral fractions (but not the amphoteric fraction) caused virtually complete mortality of N. virescens within 6 d. Additional experiments indicated that the basic, but not the amphoteric, fraction of L. hexandra inhibited ingestion of artificial diet.