144. MISC. PUBLICATION 273, U. 8S. DEPT. OF AGRICULTURE 
beetles become inactive and thus a longer period may elapse be- 
tween the time of cutting and the removal of logs, before damage 
becomes important. 
The control of ambrosia beetles is largely a matter of prevention 
of damage through the regulation of woods practice and proper 
handling of the products from the mill. Logs cut in the summer 
or fall should be removed from the woods within a week or two 
after cutting and either placed in water or run through the mill 
(56a). Logs cut late in the fall, in widwinter, or early in the spring 
will be reasonably safe until the approach of warm weather but often 
FicurE 70.—Tunnels in fir made by ambrosia beetles: Long winding tunnel made by 
Platypus wilsoni; branching tunnels made by Gnathotrichus sulcatus. 
cannot be removed before damage has occurred. Freshly sawed 
lumber. will be safe from attack if it 1s dried quickly, but some 
damage may occur in storage if the lumber is piled so as to re- 
main or become moist. Logs or wood either heavily soaked with 
water or quite dry are not suitable for attack, but the exposed parts 
of logs left floating in ponds are very apt to become infested. In 
general, the control of these beetles 1s very difficult, and prompt 
utilization or kiln drying of the lumber is about the only satis- 
factory solution (49c). A small amount of parasitism has been noted 
