In the castor bean oil efficacy test, mortality increased steadily with castor bean oil dose. More weevils died at the first day when treated with 16 ml oil and at the third day when treated with other rates. Without treatment, mortality was negligible (Table 1). The highest dose (16 ml) had a fast knock down effect on weevils while lower doses acted relatively slowly. The higher the rate, the quicker the knockdown and the greater the mortality.