Dipterous Larvcs 137 



//. Slits of the posterior stigmata sinuous or bent. Subfamily Muscinae. 

 g. Slits of the posterior stigmata bent; usually two mouth hooks. Muscina 

 stahulans (fig. 171, l), Muscina similis, Myiospila meditatunda (fig. 172, i), 

 and some of the higher Anthomyiidce. 

 gg. Slits of the posterior stigmata sinuous; mouth hooks usually consolidated 

 into one. The house-fly (Musca domesUca fig. 171, d), the stable fly 

 (Siomoxys calcitrans) the horn fly (Lyperosia irritans), Pyrellia, Psfiudo- 

 pyrellia, Morellia, Mesembrina. Polietes, et. al. (fig. 172 in part). 



Eristalis — The larvae of Eristalis are the so-called rat-tailed mag- 

 gots, which develop in foul water. In a few instances these larvffi 

 have been known to pass through the human alimentary canal 

 tminjured. Hall and Muir (1913) report the case of a boy five years 

 of age, who had been ailing for ten weeks and who was under treat- 

 ment for indigestion and chronic constipation. For some time he 

 had vomited everything he ate. On administration of a vermifuge 

 he voided one of the rat-tailed maggots of Eristalis. He admitted 

 having drunk water from a ditch full of all manner of rotting matter. 

 It was doubtless through this that he became infested. It is worth 

 noting that the above described symptoms may have been due to 

 other organisms or substances in the filthy water. 



Piophila casei, the cheese-fly (fig. 99), deposits its eggs not only 

 In old cheeses, but on ham, bacon, and other fats. The larvse (fig. 98) 

 are the well-known cheese skippers, which sometimes occur in great 

 abundance on certain kinds of cheese. Indeed, some people have 

 a comfortable theory that such infested cheese is especially good. 

 Such being the case, it is small wonder that this species has been 

 repeatedly reported as causing intestinal myasis. Thebault (1901) 

 describes the case of a girl who, shortly after consuming a large piece 

 of badly infested cheese, became ill and experienced severe pains 

 in the region of the navel. Later these extended through the entire 

 alimentary canal, the excrement was mixed with blood and she 

 suffered from vertigo and severe headaches. During the four fol- 

 lowing days the girl felt no change, although the excretion of the blood 

 gradually diminished and stopped. On the fourth day she voided 

 two half-digested larvae and, later, seven or eight, of which two were 

 alive and moving. 



That these symptoms may be directly attributed to the larvae, 

 or "skippers," has been abundantly shown by experimental evidence. 

 Portschinsky cites the case of a dog fed on cheese containing the 

 larvag. The animal suffered much pain and its excrement contained 

 blood. On post mortem it was found that the small intestine through- 



