26 



BOAED OF AGRICULTURE. 



be found on one horse. In depositing the eggs, the female 

 fly hovers around the horse, and as each egg is ready to be 

 deposited, she quickly advances and bends the abdomen for- 

 ward, with the egg at the end, and applies it to the hair, to 



Eigure 26. 



Figure 25. 



which it instantly adheres by the glutinous secretion which 

 covers it. She then retreats and prepares another egg^for 

 the same operation. This does not disturb the horse, unless 

 by a tickling sensation, causing the muscles of the skin to 

 contract with a tremulous ^ motion. The eggs contain more 

 or less perfectly developed larv£e when laid ; and when they 

 are mature, or have been a few days attached to the hair, 

 they burst open and allow the young to escape almost instan- 

 taneously, when moistened. Thus, when the horse licks itself 

 or its companions, the moisture hatches the eggs, and the 

 young larvae are transferred to the mouth by the tongue or 

 lips, and thence to the stomach, where they fasten themselves 

 to the lining membrane by their two hooks. They generally 

 occur in clusters, and are most common in the vicinity of the 

 pylorus, but are found attached to all parts of the stomach. 

 In this situation they slowly grow to be large fleshy larvae, 

 with a round body, about an inch long (Figure 25). The 

 segments of the body are provided with double rows of spines, 

 pointing backward. These are reddish with black tips. The 



Figure 25. — Bot-fly of the horse { Gastropkilus equi Leach), female, natural 

 size. 



Figure 26. — Larva of the same, enlarged. From Packard's Guide. 



