Clones of 10 F2 mite-susceptible Lycopersicon esculentum Mill. × mite-resistant L. hirsutum Humb. & Bonpl. were raised in summer and winter in the greenhouse. Leaflets from clones grown in both seasons were assayed for two-spotted spider mite survival (Tetranychus urticae Koch); Type IV, Type V, and Type VI trichome densities; and zingiberene and γ elemene concentrations. Clone, season, and their interaction were significant sources of variance of all six variables. Between season, among clones, and among clones between seasons, mite survival was inversely correlated with Type IV trichome density. No evidence for involvement of sesquiterpene presence or concentration or Type V or Type VI densities with mite survival was observed. Covariance analysis of mite survival using Type IV trichome density as the covariable removed the significance of the clone × season interaction, reduced the significance level of clonal variation, and reduced the mean square of seasonal variation. Because Type IV trichome density and mite survival were related across all sources of variation, Type IV trichome density is probably mechanistically and causally related with host-plant resistance of Lycopersicon hirsutum to mites.