288 tilE CANADIAN ENTOMOLOGIST. 



was the cause of these troubles that the result of your researches is very gratifying to 

 us, as we were in the dark whether the cause was not some fault of ours in the manu- 

 facture of the leather. You asked at what time of the year this trouble appears. We 

 have noticed it at all seasons, but had a remarkably large percentage of it in the hides 

 received during the months of September, October, Novemljer and December of last year. 

 " We have found it in hides that were bought in St. Paul, Chicago, Kansas City, 

 but think we noticed it more in hides from the southern districts. The damage to the 

 hide is a severe one, being fully 20 per cent. Taking 50 pounds as the average weight 

 of country hides it would amount to 50 cents per head, which, of course, in the aggre- 

 gate is an immense loss to the tanning interest. 



" Yours very respectfully, 



"(Signed) Pfister & Vogel Leather Co., 



" Per Fred Vogel, Jr., Mngr." 



It will be seen from this letter that this parasite occurs on cattle much 

 more frequently than has hitherto been supposed. 



It would of course be extremely difficult to treat a herd of cattle 

 affected with this parasite. Several authors recommended the same 

 treatment for cattle which is used in cases where dogs are affected with 

 the same parasite. Prevention, however, can effect a great deal, and as 

 soon as the mites are noticed on an animal, the latter should immediately 

 be isolated from the herd. 



Bureau of Animal Industry, Washington, D. C, 

 July I, 1892. 



Postscript. — Prof Riley in personal conversation with me suggested 

 the use of kerosene emulsion to destroy these parasites. The emulsion is 

 certainly worth trying, but I must confess I have not much confidence 

 that it will prove as effectual against these mites as it has against other 

 arthropode parasites. Experience has shown that nothing short of a 

 thorough rubbing in of whatever is used (benzine, carbonate of potash, 

 green soap and all the rest of the remedies recommended in various 

 books) will destroy the hair-follicle mite. 



In the discussion which followed the presentation of the paper before 

 the Entomological Club, the other varieties of Deviodex were mentioned, 

 and at the request of several members of the Club I append below the 

 measurements (in mm.) of the varieties in question [compiled from 

 Meguin, Railliet, Neumann, Ziirn]. 



/, D. f. var. hominis. 



Female : length 0.40 



rostrum 0.02 long, base 0.03 broad. 



thorax 0.09 by 0.04 



