The bark beetles colonization action is perceived by their host as a biotic stress, they response to this action secreting oleoresin which is a mixture of several compounds, some of them toxic for the insects. The first physiological reaction of them is to metabolize these toxic compounds, and subsequently use some of them as pheromones precursors. The cytochrome P450 are a metabolic system involved in regulating the titers of endogenous compounds, and in the catabolism and anabolism of xenobiotics such as plant toxins. Four gene families, CYP4, CYP6, CYP9 and mtCYP have been reported in insects. We report localization, diversity, and expression of midgut CYP from D. valens. We are studying this species because, it has been demonstrated that the monoterpenoids: á-pinene, R-(+)-á-pinene, S-(-)-â-pinene, S-(+)- á-pinene are toxic compounds, but also they are important for their chemical communication. DNA total from adults and larvae of D. valens was extracted and amplified with degenerated primers, three genes were found CYP4, CYP6, and CYP9. Subsequently, from adults and larvae midgut stimulated with á-pinene enantiomers was obtained cDNA by RT-PCR. Dot blot analysis show CYP4 gene is located in the midgut, however, CYP6 and CYP9 gene have not been amplified from this region. The CYP4 gene was sequenced and has a high similarity with CYP4G from Leptinotarsa decemliniata and Tribolium castaneum.