To determine the potential for resistance (tolerance or antibiosis) to root weevil attack on citrus rootstocks, seedlings of eight citrus rootstock cultivars were challenged with young larvae of a root weevil, Diaprepes abbreviatus L. After 6 wk of feeding and development on root systems of potted plants in a greenhouse, soil and larvae were separated from roots. Larval survival and weight, and the weight and volume of root systems, were measured and compared between infested and uninfested plants and among cultivars. For morphometric comparison of root damage, photographs of root systems were digitally imaged and integrated, and relative imaged are'as were compared. Imaging by subsoil stratum indicated that most damage occurred 4-12 cm below the surface. Larvae survived equally well on all cultivars, but larval weight showed significant variation among cultivars. Nonetheless, mean weight gain ranged from 7-fold (on Cleopatra rootstock) to 13-fold (on sour orange). Damage indexes and statistical comparison of damage indicated a wide range of tolerance among rootstock cultivars to larval feeding. Cleopatra, Carrizo, Citrus macrophylla, and a Flying Dragon × Nakon hybrid showed significant damage by larvae. Sour orange, Pummelo × Pooncirus trifoliata (2N and 4N), -and Swingle had insignificant damage. At least in reference to young ungrafted rootstocks, results indicated little antibiosis in seven of the eight rootstock cultivars studied. The exception was Swingle rootstock, on which larvae gained significantly less weight than on sour orange or Pummelo × P. trifoliata (4N). Because the damage index of Swingle was very low and differences between infested and uninfested seedlings were insignificant regarding root mass, volume, and area, a degree of both antibiosis and tolerance was indicated. Tolerance alone was indicated in rootstocks showing insignificant differences between infested and uninfested seedlings, although lack of significance was also the result of variability within cultivars