BUKEAU OF ANIMAL INDUSTBY. 119 



tained from coal-tar creosote dips, arsenical dip (low strength, 

 about 0.18 per cent arsenic trioxid), and nicotin dip (0.07 per cent) 

 with 2 per cent flowers of sulphur. 



Sheep scab. — Experiments on the ti-ansmission of scab from one 

 sheep to another indicate that sheep scab spreads more rapidly and 

 certainly to healthy animals when they mingle with infected sheep 

 than by any other method of exposure. Yards, corrals, etc., pre- 

 viously occupied by scabby sheep appear less dangerous as a source of 

 infection than is commonly sui)posed, and it is probable that under 

 winter conditions very little, if any, risk of infection remains after 

 sheep have been excluded from such places for 30 days. The form 

 of scab affecting the Rocky Mountain sheep, by some investigators 

 considered a distinct disease, appears to be transmissible to domestic 

 sheep. Under experimental conditions it was found that scab even in 

 advanced stages could be cured by dipping affected sheep in flowers of 

 sulphur suspended in water. The lack of a method of insuring proper 

 application, however, precludes the practical use of a simple suspen- 

 sion of flowers of sulphur in water as a remedy for scab. One reason 

 for the general high efficacy of lime-sulphur dip in the treatment of 

 sheep scab under all sorts of conditions appears in the fact that it was 

 found possible to cure the disease with dips containing considerably 

 less sulphid sulphur than that required by the bureau regulations. 

 In other words, the margin of safety in the efficacy of the dip is 

 such that even in cases in which for any cause the dip is below 

 standard it is likely to be sufficiently strong to effect a cure. 



Ox WARBLES. — Results of extensive observations in the South, where 

 arsenical dip is systematically used for the eradication of cattle 

 ticks, show that as a rule a material reduction occurs in the number 

 of warbles infesting cattle, sometimes amounting almost to com- 

 plete eradication. In experiments in Colorado, New Mexico, and 

 Utah, however, repeated applications of arsenical dip during the 

 spring and summer failed to prevent the appearance of warbles in 

 the backs of the cattle the following winter. This failure may have 

 resulted from the fact that dipping was not begun until after the 

 appearance of the winged stage of the warble flies, or from the fact 

 that the cattle were not dipped in the winter after the warbles had 

 reached the back and had perforated the skin. It still remains to 

 be determined whether the greatest efficiency of the arsenical dip is 

 obtained when the dipping is done during the fly season or when it 

 is done after the warbles have reached the back. 



Spinose ear ticks. — As a result of experimental work and field 

 investigations in Texas, New Mexico, and California it has been 

 determined that ordinary tick remedies will not destroy ear ticks. 

 Bland oils and crude petroleum, usually recommended for the de- 

 struction of ear ticks, are not efficacious. No satisfactory remedy has 

 been found that can be applied in the form of a dip. Hand treat- 

 ment, in which the remedy is injected into the ears of infested cattle, 

 is the only satisfactory method which has been discovered for freeing 

 them of infestation. It is necessary to clear the ear passages before 

 treatment when they are clogged with masses of ticks and wax. An 

 oil can or syringe fitted with about 4 inches of rubber tubing proved 

 a useful instrument for the application of remedies. One of the 



