The rice water weevil (RWW), Lissorhoptrus oryzophilus Kuschel, was studied on the rice plant introduction PI 321264 (moderately RWW resistant) and the variety ‘Saturn’ (RWW susceptible) in 1981 and 1982. PI 321264 sustained significantly ( P < 0.01) lower larval populations and was significantly ( P < 0.01) less preferred for feeding and oviposition than ‘Saturn.’ Manly's instar duration determination technique revealed that the length of each larval instar was 1.20 (I), 2.56 (II), 7.14 (III), and 10.33 (IV) days, respectively. Taylor's power equation and Iwao's distribution function strongly indicated a clumped distribution pattern for immature RWW on each rice genotype for both years. The equation logeTn = loge( D 2/ a / b – 2) + ( b – l/b – 2)loge n indicated that 15 samples of ‘Saturn’ and 19 samples of PI 3212564 are needed to estimate RWW larval populations with a relative variance of 10%.