338 
Warhle Flies 
presents a great contrast to blood-sucking flies. I have not succeeded 
iir keeping them alive for more than a few hours in captivity. In large 
cages they batter themselves to pieces in a short time, and in small 
cages they do not live much longer. 
Summary. 
The experiments vdth warble-fly larvae, taken in conjunction with 
the evidence of Carpenter and Glaser, lend support to the view that they 
gain an entrance through the skin. 
The hypothesis is advanced that the larvae select the gullet for 
reasons connected with their development and growth. These may be : 
a freer supply of oxygen, and a loose areolar tissue which offers com¬ 
paratively little resistance to them. 
The position of the larva under the hide is horizontal. In this 
position the skin movements affect it but slightly, or less than if the 
position were perpendicular. 
H. lineatuni does not terrify cattle as does H. bovis, the fly was seen 
ovipositing and the animals showed little uneasiness during the process. 
The seasonal activity of H. lineatiim is earlier than that of H. bovis. 
Observations were made on oviposition which confirmed those of 
Riley and Glaser. 
Two experiments were tried with larvae, to see if they would pene¬ 
trate the hide, but no definite results were obtained. 
Further proof is afforded of the terror which H. bovis inspires in 
cattle. It was observed that animals, exhausted by running, occasion¬ 
ally lay down and became more or less indifferent to the attacks of the 
fly. On these occasions the eggs were laid higher up on the host’s body. 
REFERENCES 
Carpenter, G. H. and Hewitt, T. R. (1914). The Reproductive Organs and the 
Newly-hatched Larvae of the Warble Ely {Hypoderma). Sci. Proc. Royal Dublin 
Soc. XIV. (N.S.), No. 19. 
Glaser, Hans (1913). Abstracted in Carpenter and Hewitt {q.v.), also in Bull. For. 
Ayr. hit. Can. Dep. Ayr. (May, 1914). 
Hadwen, S. Warble Flies ; the Economic Aspect and a Contribution on the 
Biology. Dep. Ayr. Can. Health of Animals Branch. Bulletin No. 16. 
Riley, C. V. (vi. 1892). The Ox Bot in the United States. Reprinted from Insect 
Life, IV. Nos. 9 and 10. U.S. Dept. Agr., Div. Ent. 
