cut expenses by reducing the 

 amount of spray wasted. 



Liquid BHC concentrates diluted 

 in fuel oil or kerosene gave slightly 

 better results in these tests than 

 those diluted in water. Oils, of 

 course, would add to the cost of the 

 insecticide, be more of a problem to 

 transport in the woods, add to the 

 fire hazard, and be very injurious to 

 living vegetation. 



Spraying Log Piles 



Logs that are sprayed incom- 

 pletely or too lightly will be poorly 

 protected. However, a BHC e- 

 mulsion diluted in water and care- 

 fully applied to the entire surface 

 of piles of insect-free cordwood 

 stacked in the usual manner, gave 

 very promising results. 



Spraying a half cord pile of pine 

 logs with two gallons of an emul- 

 sion (diluted with water) con- 

 taining 0.4 percent (by volume) of 

 the gamma isomer of BHC gave 

 97 to 100 percent reduction of 

 infestation by round-headed bor- 

 ers, ambrosia beetles, and bark 

 weevils, and the area of bark in- 

 fested by bark beetle galleries 91 

 percent. At a cost of thirty cents 

 for the spray to protect this half 



cord, it is a considerable saving 

 from the cost of fourteen cents for 

 protecting only ten logs when 

 individually sprayed. 



One gallon at the same concen- 

 tration gave 91 to 95 percent re- 

 duction of round-headed borers, 

 ambrosia beetles, and bark weevils 

 but reduced the bark beetle in- 

 fested area by only 46 percent. 



At a 0.2 percent gamma isomer 

 content, two gallons gave 87 to 88 

 percent reduction of the first three 

 types of insects, and 77 percent re- 



Above: Galleries formed by bark beetles 

 in the underside of bark. 



Left: Pupal cells of the bark weevil at the 

 surface of sopwood. 



Photos by Robert L. Coffin. 



