THE ZIMMERMAN PINE MOTH, 11 
CONCLUSION. 
It is evident that natural agencies have not succeeded in preventing, 
and will not be able in the future to prevent, serious damage by this 
moth unless man aids their efforts by disposing of such trees as have 
fulfilled their usefulness in the forest and wood lot, and which, 
instead of being an asset there, have become a menace. To end 
" spike topping" in mature stands, and to eliminate damage in 
growing timber, or at least reduce it to a negligible amount, it is 
necessary to remove (1) those trees which, below the spike, show 
branches with yellow needles (a certain indication of present infesta- 
tion), (2) those which are struck by lightning and remain green, as 
the moth usually breeds in great numbers along the lightning scars, 
and (3) those which display knobby growths on branches, they being 
in many localities the most prolific source of replenishment of the 
moth. 
