Gastricola. Bot- Flies of Solipeds and Reindeer. 71 



The ova are black, the usual color of the lips on the long hairs 

 of which they are deposited, and they are taken in by the animal 

 licking its lips, or they drop into the manger and are devoured 

 with the food. 



The larva passes through three moultings. When mature it is 

 6 to 7 lines long, and has a greenish or bluish green color. The 

 spines are arranged in a double row on each ring but on the 

 dorsal aspect they are absent in the middle of the ninth ring, 

 while on the tenth and eleventh there are none. They pass the 

 winter mostly attached in groups in the left sac of the stomach, 

 but also in the right sac, and duodenum, and exceptionally in the 

 pharynx. 



When mature and passing out through the intestines they often 

 hook themselves for a time to the rectal mucosa where they cause 

 considerable irritation and rubbing of the tail. They also pass 

 through the anus independently of defecation, and hook them- 

 selves to the skin round its outer margin, causing rubbing and 

 switching of the tail, and a stiff awkward gait. This habit, with 

 that of laying the eggs on the lips and jaw, and of hooking on to 

 the delicate mucosae of the pharynx, right gastric sac and duo- 

 denum, render this one of the most injurious of the oestridse. 



When passed the larvae are rarely found in the manure. The 

 species spend 30 to 40 days as nympha. 



CEstrus Pecorum (Gastrus Pecorum, Gastrophiltjs Pe- 

 CORUM, CEstrus Veterinus). The male fly is 4 to 5 lines in 

 length with a dense clothing of bright yellow hairs and a trans- 

 verse band of dark hairs on the back. The wings are short and 

 smoky. The female is 5 to 6 lines long, black or brownish 

 black with dirty yellow or black hairs, and smoky wings, always 

 shorter than the posterior part of the body. 



The ova are black, and are deposited like those of the oestrus 

 equi. 



The larvae hibernate in the stomach and pass through three 

 moultings. When mature they are 5 to 6 lines in length and of 

 a dark red color. They have a double row of spines on each ring 

 on the dorsal aspect as far back as the fifth, from the sixth to the 

 eighth, the spines are wanting in the centre, and behind the 

 eighth they are wanting altogether, though on the central aspect 

 they may be present even on the tenth ring. 



