52 REPORT ON INJURIOUS INSECTS FOR 1907. 



Another mite Psoroptes communis var. equi, causing a similar disease, 

 is found on the horse, and a further species Chorioptes symbiotes var. 

 equi^ and C.cynotis on dogs. 



The horse is therefore affected with three kinds of sarcoptic scabies : 



1. Sarcoptic scabies due to S.scabiei var. equi. 



2. Psoroptic scabies due to P. communis var. equi. 



3. Chorioptic scabies due to C. symbiotes var. equi. 

 Varieties of two of these occur on the dog, and although horses 



can contract sarcoptic mange by contact with that animal or any other 

 mammal susceptible of being affected with a similar form of disease, 

 such cases of transmission are rare. 



The Dog is affected with two kinds of sarcoptic scabies : 



1. Sarcoptic scabies due to S.scabiei var. canis. 



2. Chorioptic scabies due to C.cynotis var. canis. 

 According to certain authorities the first of these can be conveyed 



to the pig and horse, although such cases are uncommon. 



The second form of scabies is produced by a parasite Demodex 

 folliculorum, which lives in the hair follicles and sebaceous glands of 

 various species of mammals. 



In the dog this gives rise to what is known as Follicular Mange, 

 Black Mange, etc. 



The parasite has been found in the horse, but is rare. 



THE WARBLE FLY. 



Hypoderma lineata (Villers). 

 Hypoderma boms (De Geer). 



The Ox Warble Fly has for many years been a serious pest in this 

 country. There are two species of flies Hypoderma lineata and 

 H. bovis and many of the accounts treating of the latter species really 

 refer to the former. The aggregate loss due to " Warbles " in this 

 country is enormous, and has been variously estimated at from 2 to 

 ^7,000,000 per annum. 



LIFE- HISTORY. 



The life-history of the commoner species, H. lineata is now com- 

 paratively well known. 



The fly deposits her eggs upon the hair of the beast on the legs, but 

 they may be placed elsewhere. Usually there are several eggs together, 

 four to six on a single hair. 



The egg is about one-twelfth of an inch in length, and firmly 

 attached to the hair by a clasper-like process. 



Miss Ormerod at first thought that the eggs were deposited under 

 the skin of the animal, but later she admitted that this was contrary to 

 facts, for it had been pointed out by Bracy Clark that the ovipositor of 



