6 



OF AGRICULTURE. 



TABLE I. Flight periods of beetles used in experiments for the protective treat- 

 ments of woods with spray solutions. 



In the extreme northern States the flight period of these insects- 

 begins from two to four weeks later. In the Southern States the 

 flight period extends approximately from March 15 to November 1 

 for all species except Cyllene pictm. 



Two methods of application were employed spraying and dip- 

 ping. Dipping on the whole proved the more effective, as e very- 

 crevice in the bark was reached; it was also more economical, as a 

 smaller quantity of the solution was required. A round-bottomed 

 galvanized trough requiring only 1 inch of solution in the bottom 

 was used for this purpose. The logs were revolved in the trough 

 until all sides came in contact with the liquid. When carefully done r 

 however, spraying was nearly as effective as dipping and answered 

 very well for practical purposes. It required a fine discharge under 

 strong pressure so that penetration in all crevices was secured. 



The treated sticks were placed in several positions: (1) In shaded 

 woods on the ground, (2) in the sun on the ground, and (3) on a 

 platform off the ground in the sun. The location of the sticks had 

 considerable bearing on the results. Those in the woods were always 

 more heavily attacked and those off the ground in the sun least at- 

 tacked. This can be explained by the more rapid seasoning of the 

 wood off the ground in the sun, which thus offered less favorable con- 

 ditions for beetle attack, and by the fact that many insects will not 

 oviposit on the upper surface of logs directly exposed to the sun. 

 The logs in the woods were likewise exposed to more humid condi- 

 tions and the solutions probably leached off sooner. It follows that 



