334 SANITARY ENTOMOLOGY 



After the young had developed for several days and were sufficiently 

 large to handle readily, they were placed upon the escutcheon of a cow 

 that had been inspected thoroughly and found free from lice. Other lice 

 were left on the calf. In a given number of days eggs could be found 

 on both the calf and on the escutcheon of the cow. These eggs were 

 again watched until they hatched and in thi? way the periods of time 

 were recorded, and checked often enough to be reasonably sure of the 

 accuracy of the results. 



With the biting lice the work was much more difficult because these 

 do not remain in one place. Celluloid caps, somewhat like those used for 

 protecting vaccination points, were used to confine the lice. Areas were 

 shaved leaving small tufts of hair on which the lice could breed, and 

 adhesive tape bound the caps to the calf. The electric incubator kept at 

 the approximate temperature of the cow's skin was used to supplement 

 the observations made on the animal itself, 



CONTROL MEASURES 



A control measure or remedy for cattle lice, in order to be practical, 

 must be cheap, reasonably easy to apply, effective in killing the lice, and 

 at the same time do no injury to the cow. It should not be so poisonous 

 that the accidental consumption by animals would endanger their life. 

 At the same time the material used for control should be commonly sold, 

 and thus be within the reach of purchasers even in the remoter country 

 villages. 



Clipping. — Clipping the stock over the portion of the animal most 

 likely to be infested is not an uncommon practice, and, where the hair 

 is long and the animal is ver^^ badly infested, it helps to bring the oil 

 or wash where it will be most effective. We have found, however, that 

 animals that have been clipped are more liable to show a considerable 

 scurfing of the skin because the application reaches the skin more quickly 

 and in larger quantities than when it is held on the hair and thus reaches 

 the skin gradually. There are those who feel that the animals do not 

 look as well when clipped. 



If control measures are used early, thoroughly, and repeated through- 

 out the winter, clipping will be unnecessary. 



OILS 



Raw Linseed Oil. — Of the many different measures for the control of 

 lice on dairy cows and young stock, raw linseed oil gave the best results 

 from the standpoint of economy of material and labor of application, 

 killing the lice, but not injuring the skin, and at the same time not 



