20 



BOAED OF AGRICULTURE. 



some writers, they pierce the skin, by means of their peculiar 

 gimlet-like ovipositor ; but others deny this, and say that the 

 eggs are merely attached to the skin, and that the young 

 larvae, which very soon hatch, eat their way in. At any rate 



Figure 22. Figure 23. 



the cattle are often greatly alarmed by their attacks, and run 

 frantically about, sometimes even taking to the water for 

 safety, which would hardly -be the case unless they had suf- 

 fered pain from their attacks. Working oxen, when thus 

 attacked, sometimes cause serious trouble. 



The larvae having entered the skin increase the size and 

 depth of their burrows as they grow larger, but always keep 

 up an opening with the exterior, and keep the posterior end 

 of the body, in which the breathing pores are situated, near 

 this opening to get air. In this way they cause, by the irrita- 

 tion and inflammation that they produce, tumors or abscesses 

 of considerable size beneath the skin, and live upon the 

 matter formed by the inflammatory action. When young, 

 they are white, but afterwards become brownish ; when ma- 

 ture, deep brown. 



They have transverse rows of minute hooks ; the narrower 

 rows are on the posterior part of each segment, and the hooks 

 point backward ; those of the wider rows, point forward. These 



Figure 22. The Bot-fly of Cattle (Hypoderma bovis Latreille), considerably en- 

 larged. 



Figure 23. The full grown larva, enlarged. Both from Packard's Guide. 



