Toxicity and protectant potential of monoterpenoids viz.,eugenol,zimtaldehyde β-pinen,and diatomaceous earth (DE),i.e.Protect-ItTM and Silico-Sec(@) against Callosobruchus maculatus,Sitophilus oryzae and Triboliun castaneum were investigated in the laboratory using contact toxicity and grain treatment assays.Essential oils applied impregnated on filter paper,topically,whole grains were highly toxic to all the three species.Beetle mortality was dosage-dependent.100% mortality at 1day after treatment was achieved with eugenol against C.maculatus at 5μl/disc in filter paper test.Zimtaldehyde and βopinen at 5μl/disc were highly toxic to the adult beetles 1 day after impregnated filter paper treatment.Eugenol,zimtaldehyde and fβ-pinen were more toxic at 5μl/insect against adult beetles 2 day after topical application method.In a whole grain treated method 100% mortality was achieved against all adult beetles 1day after exposure with eugenol,zimtaldehyde and β-pinen at 5μl/kg.Protect-ItTM and Silico sec(@) were highly toxic to the adult beetles 1 day after whole grain treated method at 500 ppm/kg.Eugenol completely inhibited to produce any adults after 4 weeks when treated as whole grain at 5μl/kg,while a very few number of adult emerged from zimtaldehyde and β-pinen treated grain at the same exposure and dose.Both the DEs also inhibited adults emergence at the same treatments.These naturally occurring monoterpenoids and DE could be useful for managing populations of stored-products pest.