Armored scale (Mctaspitiotus yunnansls Tang) is a common leaf pest on needles of Evelynia Keteleeria (Keteleeria, evelyniuna). In ordinary stands, the percentage of trees infected by armored scales is about 70%, but the density index of insect occurrence is only about 2% and can hardly do any harm.As our study shows the slow growth, weak vigour and disturbance of normal physiological processes of the tree caused by the serious impact of hydrogen fluoride from phosphate fertilizer plant are due to some bioch...