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. 
Kerosene-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 of 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. 
