42 MASS. EXPERIMENT STATION BULLETIN 436 



Percent Prevention 

 Gesarol A-20 (20% DDT wettable powder) and water 



(18 grams — 3785 cc, 195 cc.) 90.3 



Gesarol emulsion (20% DDT) and water 



(1-400,185 cc.) 84.0 



(1-200. 179 cc.) 94.5 



Kerosene alone (135 cc.) 98.8 



Used crankcase oil alone (169 cc.) 94.6 



No. 2 fuel oil alone 



(42 cc.) 86.1 



(123 cc.) 100.0 



(166 cc.) 99.2 



(213 cc.) 100.0 



Orthodichlorobenzene and No. 2 fuel oil 



(1-4, 113 cc.) 100.0 



(1-8, 54 cc.) 96.7 



(1-8, 115 cc.) 100.0 



(1-8, 132 cc.) 100.0 



(1-12, 105 cc.) 98.0 



(1-16, 107 cc.) 99.1 



At the same location other elm logs were sprayed six times at three-week 

 intervals beginning May 31, with the following results. The proportions and 

 amounts of spray indicated were used for each application. 



Percent Prevention 

 No. 2 fuel oil alone (176 cc.) 100.0 



Gesarol A-20 and water (18 grams - 3785 cc, 164 cc.) 84.2 



Gesarol emulsion and water 



(1-400, 164 cc.) 87.1 



(1-200. 158 cc.) 90.3 



Sprays to Kill Scolytids Breeding in Elm Logs. (W. B. Becker.) At Spring- 

 field, the following spray mixtures were applied on July 20 to the entire bark sur- 

 face of scolytid-infested elm logs up to 6 and 10 inches in diameter with bark up 

 to one half and three quarters inch thick in the different tests. The percentages 

 of control are based on the number of exit holes per brood gallery in the late fall 

 compared with those in unsprayed logs. Brood galleries of Scolytus muLtistrialus 

 Marsham were more abundant than those of Hylnrgopinus rufipes (Eich.) in 

 these logs. The figures in parenthesis following each spray mixture indicate the 

 proportion of ingredients and the amount of spray applied per square foot of bark. 



Present Control 

 Creosote and kerosene, strained (1-4. 189 cc.) 96.5 



Orthodichlorobenzene and No. 2 fuel oil (1-8, 208 cc.) 91.7 



No. 2 fuel oil alone (200 cc.) 69.8 



Kerosene alone (186 cc.) 59.6 



Gesarol emulsion (20% DDT) and water 



(1-400, 150 cc.) 4.6 



(1-200. 133 cc.) 2.3 



Gesarol A-20 (20% DDT wettable powder) and water 



(18 grams - 3785 cc, 181 cc) 0.0 



