The boll weevil and the thurberia weevil are morphologically similar variants of the same species. The Polymerase Chain Reaction procedure was used and restriction digestion patterns of the PCR products were compared. A number of individuals have been examined from three Arizona thurberia weevil populations and compared with individuals from Texas and northeastern Mexico boll weevil populations. The results indicate apparent diagnostic restriction fragment differences between the thurberia weevils and the boll weevils. Polymorphism was also observed within the two weevil types.