Volume VIJ 
MARCH, 1915 
No. 4 
WARBLE FLIES. 
A FURTHER CONTRIBUTION ON THE BIOLOGY OF 
HY POD ERMA LINEATUM AND HYPO DERM A BOV IS. 
By SEYMOUR HAD WEN, D.V.Sci. 
Veterinary Research Lahoratory, Agassiz, B.C. 
(With Plates XXIY and XXV.) 
The experiments here recorded were carried out in the year 1913 
and the spring of 1914; they were performed with larvae taken from 
the gullets of steers. Some observations were subsequently made on 
the habits of the adult flies and the process of oviposition. The protocols 
of two experiments are given first, and the explanation of these follows. 
Two Experiments with Larvae taken from the Oesophagus. 
Calf A. The calf used for this experiment was born on Sept. 28th, 
thus excluding the chance of its having been attacked by warble flies. 
On Dec. 1st, twelve larvae were extracted from the gullets of two steers. 
These were removed carefully so as to avoid injury. As each was 
extracted it was placed between two folds of gullet and kept in a warm 
place. The removal of the larvae took about half an hour. An incision 
was made in the right hind-quarter of the calf and the larvae were 
dropped one by one into this pocket. The wound healed rapidly and 
no traces of the larvae were seen until February 2nd, when four warbles 
were discovered on the animal’s back. All except one were on the right 
side. Two of these became absorbed later, and two remained till after- 
March 10th, when they also became absorbed. 
Calf B. On January 25th, 26 seccmd-stage larvae were secured as 
in the preceding experiment from four gullets. They were placed in a 
pocket on the left hind-quarter of a November calf. On February 2nd, 
several warbles could be felt on this animal’s back. One of them was 
Parasitology vil 
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