42 MASS. EXPERIMENT STATION BULLETIN 428 



Sprays to Kill Scolytids Breeding in Individual Elm I>oj»s. (W. Ij. Becker.) 



At Amherst, the following spray mixtures were applied to the entire bark surface 

 of individual elm logs (up to 12 and 21 inches in diameter with bark up to 5/8 

 and 3/4 inch thick) and gave the indicated percentages of control based on the 

 number of exit holes per brood gallery in the late fall. The figures in parentheses 

 following each spray mixture indicate the proportion of ingredients and the 

 amount applied per square foot of bark surface. 



Percent Control 



Orthodichlorobenzene and No. 2 fuel oil (1-8, 135 cc.) 99.9 



Creosote and kerosene (1-4, 119 cc.) 97.6 



Kerosene alone (1 1.^ cc.) 91.1 



Orthodichlorobenzene U. I. Lestoil, and water (l-0..'5-8, 166 cc.) 80.7 



The Prevention of Elm Scolytid Infestation by vSolar Heat. (W. B. Becker.) 

 At Amherst, freshly cut elm logs lying in a north-south rlirection in the sun were 

 rolled 180 degrees of their circumference (1) every week and (2) every three weeks 

 during the early season oviposition period (May 18-June 23). After the latter 

 date none were disturbed until after the beetle's active season had ended. Com- 

 pared with the nujnber of exit holes per square foot of bark in unturned check 

 logs in the sun, 99.7 percent control resulted from weekly turning of logs between 

 3 and 13 inches in diameter, with bark up to 7/16 inch thick. Turning every 

 three weeks gave 93.5 percent control in logs between 4 and 21 inches in diameter, 

 with bark up to H '"ch thick. Ilylur^opinus rufipes was the only elm scolytid 

 found in the logs. 



At Westfield, similar experiments c(jnducted between June 10 and July 15 

 with logs up to 7 inches in diameter having bark up to 5/8 inch thick gave 100 

 percent control with both treatments. //. rufipes was much more abundant than 

 Scolyliis muhislriatus in the logs. 



At both localities the beetle galleries reached a more advanced .stage in the 

 logs which were turned every three weeks than in those turned every week. The 

 larger logs usually had more brood galleries than those of small diameter, those 

 less than 5 inches in diameter having none at all even among the unturned check 

 logs. 



Combined Use of Sprays and Solar 1 leat on Individual Elm Logs to Prevent 

 Elm Scolytid Infestation. (VV. B. Becker.) At Amherst, slightly more than the 

 upper half of freshly cut, uninfestefl elm logs, 3 to 14 inches in diameter, with 

 bark up to 1 inch thick, and lying in a north-south position in the sun, were 

 sprayed in the spring with creosote and kerosene (strained), 1 to 4 by volume, 

 and then rolled over so the sprayed side was turned down. Compared with 

 unsprayed logs similarly placed, 99.8 percent prevention resulted, based on the 

 number of exit holes found per square foot of bark after the beetle's active season 

 had ended. The only area infested was a small patch of bark on the under side 

 of one log, which was not covered by the spray. Ilyliirgnpiniis rufipes was the 

 only elm scolytid present. 



At Westfield, 100 percent contrrjl resulted from similar treatment of elm logs 

 up to 7 inches in diameter, with bark up to 3/8 inch thick. H. rufipes was much 

 more abundant than Scolyius muUislrialus in the control logs. 



Some logs less than 10 inches in diameter, which were similarly treated at 

 Amherst on July 2, 1943, and which were left exposed to beetle attack through 

 1944, did not become infested. However, since unsprayed check logs which lay 

 in the .sun did not become infested either, it may be assumed that these logs were 

 too seasoned for scolytid infestation by the spring of 1944. 



