Essential oils were extracted by steam distillation from Cymbopogon nardus, Cymbopogon schoenanthus and Ocimum basilicum. They were used in fumigation to investigate their absorption by cowpea, Vigna unguiculata seeds during treatment and their residual effects on adult Callosobruchus maculatus (Fabricius) survival and female reproduction, and seed germination. During the treatment, seeds absorbed the essential oil compounds differently. Treated seeds dried for 24 h and then maintained at 20, 30 and 50°C for degassing continued releasing terpenic compounds. After a 72-h exposure, adult C. maculatus mortality was less than 50% in the presence of treated and degassed seeds. The treated seeds did not affect reproduction in female C. maculatus nor seed germination.