Shots of displays of the various stages in the growth of the gypsy moth. An egg mass, the larval stage, the pupal stage and the adult. HAS over forest ravaged by the gypsy moth caterpillar. Interior of wood, bare trees, man walking to early model touring car. Cut to mass of caterpillars stuck to branch of tree. Animation map shows progress of invasion of the gypsy moth from Boston into southern Quebec. Sequence on men scouting for forerunners of the gypsy moth invasion. Men are shown examining trees, discovering egg masses. MCUs of such masses of eggs. Several shots of men taking measures to fight the menace, sawing down badly infested tree limbs, chopping down smaller trees, burning brush, examining rocks, wooded structures and applying creosote to destroy egg clusters. Cordwood is loaded into wagon. MCU of egg cluster on pieces of wood. Shots of men inspecting Christmas trees in light snowfall. Cut to certificate of inspection. MCU of tree trunk with gypsy moth caterpillars on it. Stone walls are singed to destroy undiscovered egg clusters. Foliage is sprayed with arsenate of lead from truck-mounted, high intensity sprayers. MCU of bilingual notice re: danger from poison on leaves.