The deciduous stands have suffered an important impact through the strong gradations developed by the defoliating caterpillars that remind the species, Lymantria disappear L., Operophtera brumata L., Erannis defoliaria Cl., Tortrix viridana L., Hyphantria cunea Drury, etc., making special efforts to avoid defoliation that, produced repeatedly, would have led to their drying. International efforts to conserve the natural environment focus on vast ecosystems with high biodiversity, relatively untouched cosystems, or where they are endangered plant or animal species. The optics regarding the use of chemicals, which contribute to the pollution of the environment, have also changed, their alternative being the biological control , which lately has seen a strong development especially in the case of the application of bacterial treatments and the use of zoophagi.