During a 2-yr study investigating the fecundity of the sugarcane borer,Diatraea saccharalis(F.), 607 pupae were collected on four gramineous hosts. Weight, length, and diameter of sugarcane borer pupae collected on corn,Zea maysL. cv. Merrit, and a sugarcane borer-susceptible sugarcane (a complex hybrid ofSaccharumspp.) variety, CP 61-37, were greater (P<0.05) than those of pupae collected on johnsongrass,Sorghum halapense(L.) Persoon. Female pupae collected on a moderately resistant sugarcane variety, CP 65-357, weighed significantly less (P<0.05) and were shorter than those collected on CP 61-37 or corn. The sex ratio of sugarcane borer was independent of host plant. The best model for predicting sugarcane borer fecundity was that of a linear regression on pupal weight, with fecundity increasing at 4.3 eggs for each milligram increase in pupal weight, regardless of host or year from which the pupae were collected. Fecundity of moths collected from corn and the susceptible sugarcane variety was greater (P<0.05) than that of moths collected from johnsongrass or the moderately resistant sugarcane variety. The potential finite daily rate of increase of sugarcane borer populations was determined to be 1.132 on corn and CP 61-37, 1.128 on CP 65-357, and 1.119 on johnsongrass.