EXPERIMENTS WITH SPE>Y 



LOGS. 



the most severe conditions for dipping and spraying tests were pre- 

 sented by those logs in the woods on the ground, and for this reason 

 the discussion of results obtained is based on the results in treated 

 wood placed in this position. Where there was marked difference in 

 the amount of sunlight or in the sun temperature special note is made 

 of the fact. 



The thickness of the bark had a certain bearing on the results. 

 Thick-barked pine logs present much more favorable conditions for 

 the attack of all insects concerned. In some cases a treatment was 

 very effective on thin-barked pine logs whereas treated thick-barked 

 logs became Heavily infested. The effectiveness of a treatment, there- 

 fore, was judged by the results following in the case of thick-barked 

 logs. 



TREATMENTS AND RESULTS. 



Creosote oil alone. Pine and hickory dipped and sprayed. No attack three 

 months after treatments except a few insects of type 4 in crevices of sprayed 

 stick. 



Creosote oil and kerosene. All mixtures of kerosene and creosote oil give a 

 tarry precipitate which must be strained out or allowed to settle before the 

 liquid is used in a spray pump. This material was suggested by Dr. A. D. 

 Hopkins. 



Equal parts creosote oil and kerosene. Pine, ash, juniper, and hickory, 

 sprayed and dipped. Results as in the case of creosote oil alone. 



One part creosote oil and two parts kerosene.- Treatment as in the next pre- 

 ceding paragraph. Results as in the case of creosote oil. 



One part creosote oil and three parts kerosene. Pine logs dipped. No attack 

 after three months. 



One part creosote oil and four parts kerosene. Pine logs dipped. No attack 

 after three months. 



One part creosote oil and eight parts kerosene. Pine logjs sprayed and dipped 

 were attacked after two months by a few insects of type 4. 



Creosote oil alone and mixtures of creosote oil and kerosene gave excellent 

 results. Everything considered, much better results were obtained with them 

 than with any other material. Dilutions of creosote oil containing from 1 to as 

 many as 8 parts of kerosene were effective, and perhaps an even greater dilu- 

 tion would be effective on absorbent barks such as ash or juniper. These mix- 

 tures act as repellents (in no cases were insects observed to oviposit where the 

 liquid was present) and they "stand up" very well in wet weather. 



One part water-gas tar distillate* and three parts kerosene. Considerably 

 more precipitate results from this mixture than from that of creosote oil and 

 kerosene; consequently it is more troublesome to handle. Pine logs were 

 sprayed and dipped. The results were similar to those with creosote oil. 



One part coal-tar road surfacing material and three parts kerosene. Pine 

 logs dipped with this mixture were attacked after 15 days by insects of type 

 4 and later their condition was but little better than that of the controls. 



2 A distillate prepared from water gas. 



