144 



MISC. PUBLICATION 273, U. S. DEPT. OF AGRICULTURE 



beetles become inactive and tlms 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 



FiGUKE 70. — Tunnels in fir made by ambrosia beetles : Long winding tunnel made by 

 Platypus wilfsoni J branching tunnels made by Gnathntrichus sulcatum. 



cannot be removed before damage has occurred. Freshly sawed 

 lumber will be safe from attack if it is 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 

 wat^r 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 is very difficult, and prompt 

 utilization or kiln drying of the Imnber is about the only satis- 

 factory solution {Jf9c). A small amount of parasitism has been noted 



