Laboratory evaluation of Calotropis procera, Alstonia boonei, Jatropha curcas and Argemone mexicana latex as biopesticide against cowpea bruchid, Callosobruchus maculatus (Fab.) [Coleoptera: Chrysomelidae] were evaluated at ambient temperature and relative humidity of 28±2 o C and 75±5% respectively. The plants latex was tested at rates of 0.5 ml, 1 ml, 1.5 ml and 2 ml / 20 g of cowpea seeds. Adult mortality and adult emergence of the insects were investigated. Results showed that at rates of 1 ml, 1.5 ml and 2 ml/ 20 g of cowpea seeds, A. boonei latex evoked 100% mortality of adult cowpea bruchid after 4 days of post treatment. This is followed by C. procera and J. curcas which caused 100% mortality of cowpea bruchid at rates of 1.5 ml and 2 ml / 20 g of cowpea seeds while the least effective plant Argemone mexicana latex. There was no adult emergence in seeds treated with A. boonei latex at tested concentrations and C. procera and J. curcas at rates of 1.5 ml and 2 ml / 20 g of cowpea seeds compared with untreated that had 87.75% adults emergence. The results obtained from this study revealed that Alstonia boonei, Calotropis procera and J. curcas latex were effective in controlling of C. maculatus and could serve as an alternative to synthetic insecticides for the protection of stored cowpeas against bruchids.