A standard dissecting microscope has been adapted to study the life history of Chermes piceae Ratz. in situ on the trunks of Pacific silver fir (Abies amabilis Dougl. Forbes) This micrographic technique, devised for re-examination of stationary individual insects, consists of mountings for fastening the microscope to the tree, a net reticule placed in one microscope eyepiece to provide grid coordinates and a flashlight fastened to the body of the microscope to illuminate the insects on the bark.