108 PROC. ENT. SOC. WASH., VOL. 22, NO. 5, MAY, IQ2O 



At Vicksburg and Delhi, Miss., during May, 1918, ash logs 

 cut at various times during the preceding six months, some of 

 which had been submerged for various periods, were exposed to 

 the sun as described for the mesquite. Most of the earlier cuts 

 were infested with ambrosia beetles and Neoclytus erythrocephalus 

 larvae, while many of those recently felled contained no insects. 

 Weekly turning of these logs killed all insects on or beneath the 

 bark and the uninfested logs were not subsequently .attacked by 

 the following November. 



At Falls Church, Va., June 1, 1919, ash, pine, oak and hickory 

 sticks that had previously been submerged in water (i 1 2 and 

 x 1 o months and, therefore, particularly suitable for the attack of 

 ambrosia beetles were removed from the water and exposed to 

 the sun. They were turned weekly during June, July and August. 

 Ambrosia beetles immediately attacked on the under surface. 

 The first turning killed all these beetles before they had entered 

 more than one-quarter inch into the sap wood. On following 

 turnings the underside was likewise attacked and the beetles 

 subsequently killed. This was repeated for four weeks, after 

 which the sticks were sufficiently dried to prevent further attack, 

 and no beetles penetrated far enough into the wood to cause 

 any injury. 



Experiments at the same place in July, 1919, demonstrated 

 that various species of Scolytid adults and larvae and Monoham- 

 ni us titillator larvae in pine could be killed or their attack pre- 

 vented by the same measures. 



Experiments have since been undertaken to determine the 

 sections of the country where this method can be utilized, the 

 season of year during which it is effective, and what constitutes 

 killing temperatures and their relation to humidity. A few ob- 

 servations have shown that the inner bark on logs exposed to 

 direct sunlight may reach a higher temperature than the sur- 

 rounding air by as much as 00 , depending on the locality, the 

 condition of the sky and the angle of the sun's rays. 



Ac! mil date of publication June 14. IQ2O 



