92 



of it, and 239,484 square miles in Texas were released from such 

 quarantine. During a similar campaign against cattle scabies 642,831 

 cattle were dipped and a few scattered outbreaks in several States 

 were quickly brought under control. The remaining area under 

 Federal quarantine, 3,817 square miles in Texas, was released. Horses 

 and mules to the number of 545 were dipped for scabies under Bureau 

 supervision. 



The Tick Eradication Division made greater progress than in 

 any previous year in the work of exterminating the ticks which 

 transmit Texas fever to cattle. Areas that aggregated 67,308 square 

 miles, having been freed of ticks, were released from quarantine. 

 Inspections or dippings to the number of 34,927,959 were made of 

 cattle, as against 24,390,721 in the preceding year. There were in 

 operation 26,470 cattle-dipping vats where cattle were dipped under 

 Federal State supervision. The work accomplished in tick eradication 

 in the last year makes available 86 counties and 37 parts of counties 

 into which better-bred cattle from tick-free States may be taken with- 

 out danger of loss from tick fever. A consequent increase in meat 

 and dairy products may be expected, and in addition the hides of all 

 cattle will be improved to a degree which will render them 20-50 

 per cent, more valuable. 



During the autumn of 1917 and the spring of 1918 much attention 

 was given to the possibility of the conveyance of hog cholera by 

 insects, lice, flies, mosquitos and other insects being studied, and 

 much valuable information obtained. In some cases cholera has 

 been transmitted by means of flies, but it is too early to express a 

 definite conclusion on the relation of insects to the spread of this disease. 



In the Zoological Department the investigation of parasitic diseases 

 of animals and the study, collection and determination of animal 

 parasites have been continued. Experiments showed that it was 

 impossible to protect cattle from infestation with ox warbles [Hypo- 

 derma bovis] by dipping or spraying with various remedies. Cattle 

 lice were found to be effectively eradicated by means of coal-tar creosote 

 dips when reasonably good water was used. The best treatment 

 for the louse infesting pigs [Haemato^nnus suis] was shown by several 

 series of experiments to be dipping. Wallows, medicated with coal-tar 

 creosote-dips, pine-tar, crude petroleum or bland oils, and rubbing 

 posts treated with crude petroleum, reduced the number of parasites 

 to such an extent that they caused little or no damage, though neither 

 of these methods resulted in complete eradication. The best results 

 were obtained with a i of 1 per cent, solution of pine-tar in the 

 wallows. Crude petroleum and coal-tar creosote dips proved to be 

 more effective when applied from an ordinary sprinkling can than 

 when used in wallows or on rubbing posts. Mange in pigs was studied 

 experimentally by different methods of treatment, but the work has 

 not progressed sufficiently to warrant definite conclusions. The 

 treatment of large numbers of cattle with various preparations for 

 ear ticks [Ornithodorus megnini] showed that there was no better 

 remedy than pine-tar 2 parts, and cotton-seed oil 1 part. Special 

 attention was given to sarcoptic mange of cattle, the results of experi- 

 ments showing that sarcoptic scabies [Sarcoptes scabiei var. hovis] 

 can be eradicated by 4 dippings in lime-sulphur or nicotine, the 

 interval between dippings being from 6 to 10 days. 



