﻿THE CATTLE GRUBS OE OX WAEBLES 7 



mum development in numbers in parts of Germany. They are 

 known to be abundant in Switzerland, Denmark, Holland, and the 

 British Isles, and probably occur throughout Europe. They are 

 abundant throughout the greater part of the United States and 

 southern Canada. 



It is verj^ doubful if either species of Hypoderma will ever become 

 an established pest in the Tropics or subtropics. Both have been 

 repeatedly introduced there with cattle, but there are no records of 

 subsequent breeding. It is true, however, that positive information 

 is very meager as to the presence of Hypoderma in parts of the 

 world other than those in which it is a pest. A. H. Ritchie informs 

 the writers that in the West Indies he has never seen the warble 

 except in four animals imported from the United States. 



Xo records are known to the writers of the occurrence of Hypo- 

 derma in South America. The genus is replaced in tropical America 

 by Dermatobia, and its similar injury to hides leads some to think 

 Hypoderma is present there. 



Hypoderma is not indigenous to South Africa and apparently has 

 never become established through introductions. Lounsbury (6'^) 

 and Hutcheon (47) state that they have no knowledge of the occur- 

 rence of either species of Hypoderma in native cattle in the Union 

 of South Africa. Lounsbury saj^s in a letter: "Now and then 

 warbles are found under the skin of animals imported within a 

 matter of months, but I have never heard of any being found in 

 animals bred in the country or here for a number of years." 



Howard (46) reports the finding of larvae of II. linsafum in 

 Mozambique, East Africa, but does not say if from native or im- 

 ported cattle. 



James Bequaert has informed the writers that in his extensive work 

 in Belgian Congo he has never seen or heard of an authentic case 

 of the occurrence of either species of Hypoderma in that country. 

 He also directs attention to the statement of Roubaud {85), who has 

 paid special attention to dipterous parasites of mammals in Belgian 

 Congo and French West Africa, that he has never seen Hypoderma 

 on cattle in that reg'on. In northern Africa, Hypoderma evidently 

 occurs. E. E. Austen writes that the British Museum contains a 

 male of II. bovis from Algeria near Bone, collected May 5, 1896, by 

 A. E. Eaton. Vaney (J04) in 1011, states that II. hoins occurs in 

 Algeria. WiHcocks {JJ2), in 1018, says that //. hovis occurs in 

 Egypt, but whether or not it is a common pest is not known. 



In Australia, likewise, neither species seems to have gained a foot- 

 hold. Try on, in 1006 (100), and again in 1012 (WI) reported the 

 apparent stamping out of a local introduction in the Richmond 

 district. Poimrl {70} describes the appearance of warbles in im- 

 ])orted stock and adds, "It is diflicult to assign any definite reason 

 why the cattle grub fly has not become established in Queensland. 

 Evidently the conditions of envii-onment are unfavorable." Smit 

 (.9,2) states that II. bovis imported into the Dutch East Indies from 

 Holland apparently failed to establish itself, as no records in native 

 cattle liave been made. 



Regarflinir the nonoccurrence of Hypodeniuj in Hawaii, Van 

 Dine and Xorgaard {108) write: "One and possihily both of the 

 hot flies attacking cattle have l)een brought to Hawaii with im- 



