322 
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THE WARBLE-FLIES OF CATTLE. HYPODERMA 
BOV IS AND H. LINEATUM. 
By CECIL WARBURTON, M.A. 
Molteno Institute for Research in Parasitology. 
(With 3 Text-figures.) 
CONTENTS. 
PAGE 
Introduction ............ 322 
I. Bionomics of H. bovis and H. lineatum according to our present 
knowledge ........... 323 
II. The evidence discussed: 
The Flies.327 
Oviposition ......... 329 
Hatching of the eggs . . . . . . . . 331 
Penetration . . . . . . . . . 331 
The larva within the host ....... 333 
III. Injuries to cattle .......... 336 
IV. The flies differentiated ......... 338 
Introduction. 
The phenomenon of tumours in the backs of cattle from which in due time 
grubs emerge has been known from very early times. So, also, has the 
phenomenon of “gadding,” now known to be due to Warble flies, and it is 
sufficient to cite the familiar and most graphic account given by Virgil 1 . 
Since, however, the origin of the grubs in the tumours was entirely unknown 
amd the “gadding” was usually attributed to members of the Tabanidae, 
allusions to these phenomena earlier than the 18th century have no value 
except as indicating the antiquity of the pests. 
At the beginning of the 18th century Vallisnieri set himself to discover 
the insect of which the warble maggots are the larvae, and after much 
expenditure of time and money he at length succeeded (in 1710) in breeding 
out a single rather damaged imago, which is described and figured in his 
Ojjere 2 published by his son in 1733. Therewith begins any exact knowledge 
we possess on the subject, and though more than two hundred years have 
elapsed, and the problem has been attacked, somewhat spasmodically, by a 
host of investigators, there still remain obscure points in the bionomics of 
these remarkable insects. Nevertheless we have now arrived at a stage where 
1 Georgies in. 146-151. 
2 Vol. i. p. 28, fig. 10. 
