Four types of plant oils (fenugreek, jojoba, sweet almond and moringa) were evaluated for their effectiveness against adults of the cowpea beetle, Callosobruchus maculatus (F.) under constant conditions at 29 ±1 ºC and 70 ± 5% RH. Eight concentrations of each oil (1, 5, 10, 15, 20, 25, 30 and 35% v/v) were tested on adult mortality percentage and some biological effects. The obtained results showed that the percentage of adult mortality increased by increasing both of concentration of the tested plant oil and exposure period. Generally, jojoba oil was the most effective plant oil against C. maculatus recording the highest percentage of adult mortality (56.67, 80.00 and 63.33%) regardless of the concentration after 24, 48 and 72 hr. post – treatment.