10 BULLETIN 1228, U. S. DEPARTMENT OF AGRICULTURE. 



Pure, heavy coal-tar creosote oil was entirely efficient. Kerosene 

 was moderately efficient and under some conditions quite so, but it 

 lacked the body and lasting effect of the heavier oils. Gasoline was 

 of little value. 



Paradichlorobenzene and naphthalene when dissolved in kerosene 

 and gasoline were not more efficient than the pure oils themselves, 

 except that naphthalene in gasoline gave results somewhat superior 

 to pure gasoline. 



In a whitewash, 11 per cent of creosote oil and 10 per cent of crude 

 carbolic acid were efficient, but 8 per cent of the latter was of no 

 value and 11 per cent of phenol was only moderately efficient. 

 These mixtures are wholly mechanical and must be applied imme- 

 diately. They are less satisfactory than emulsions or combinations 

 of oils. 



Oil mixtures of kerosene and cresol and of kerosene and carbo- 

 lineum were quite efficient even when the coal-tar oils comprised 

 only 10 per cent of the mixture. A preparation of 20 per cent of the 

 heavier oil would insure more body to the material ; in fact, the higher 

 the percentage of heavy oil the more lasting will be the effect. 



Keroserfe-oil emulsion containing 77 per cent of oil was efficient 

 when diluted 1 to 3 or 25 per cent. This gives an oil percentage in the 

 spray of 19.25 per cent. Greater dilutions were less efficient, but two 

 or more applications of a spray containing not less than 16 per cent 

 of oil should be of considerable value. 



Emulsions of heavy mineral oils containing approximately 82 per 

 cent of oil were efficient at strengths of 1 to 2.5 and 1 to 3 in water, 

 the actual sprays containing, respectively, 23.49 and 20.65 per cent of 

 oil. Out of two tests in which the oil content of the sprays was 16.5 

 and 16.4 per cent, respectively, one spray was efficient and the other 

 moderately so. Sprays with less than 16 per cent of oil were ineffi- 

 cient, but two applications at this strength would be of much value. 



Chicken-house tests with coal-tar disinfectants were made with 

 sprays containing as much as 4.8 per cent of oil. At this strength a 

 single application was moderately effective. In nest boxes as little 

 as 2 per cent of oil was efficient. 



Kerosene-oil emulsion diluted to 19.25 per cent oil appeared 

 superior to pure kerosene, perhaps because oi its greater penetrating 

 power. Emulsions of coal-tar oil diluted to 4.8 per cent oil were 

 inferior to straight tar oils and to mixtures of coal-tar and mineral 

 oils. 



RECOMMENDATIONS. 



Heavy oils from coal tar and wood tar, or such oils diluted with a 

 lighter oil, such as kerosene, so that not less than 20 per cent of the 

 mixture is heavy oil, will successfully control chicken mites, provided 

 the premises are thoroughly sprayed and the material not stinted. 



A heavy mineral-oil emulsion containing at least 20 per cent oil in 

 the actual spray will be efficient under similar conditions. 



