584 THE ANIMAL PARASITES OF MAN 



live in water, no matter how foul, and in liquid manure. They have occasionally 

 been obtained in foul drinking water by human beings and from eating watercress 

 improperly washed or from badly kept beds. Austen (Trans. Soc. Trap. Med. and 

 Hyg., iii, No. 6, p. 221) records that in the autumn of 1907 a number of the larvae 

 of the common drone fly (Eristalis tena.v] were passed per rectum by a woman in 

 Hampshire who had recently arrived from Fiance. The patient had eaten a con- 

 siderable quantity of watercress before leaving Fiance. I have twice found small 

 Eristalis larva? clinging by their long tails on watercress served at table. 



Family. Drosophilidae. 



Small, rather plump flies, with short, broad abdomen, with bristles on the head 

 and legs. Often abundant in decomposing fruit, and may occur in dense masses. 



Drosophila melanogaster, Br. 



The larvae of this fly occur in over-ripe fruit and in fungi, often also in human 

 habitations, and live in substances undergoing acid fermentation (vinegar, decaying 

 fungi, rotting fruit, in damaged spots in diseased trees), much more rarely in animal 

 substances, and they occasionally gain access to the human intestine (for example, by 

 the medium of sour milk). When introduced in any quantity, they cause vomiting 

 or attacks resembling colic ; when taken in the pupal stage no unpleasant results 

 are produced. 



Family. Muscidae. 

 Teichomyza fusca, Macq. 



Syn. : Scatella tirinaria, Rob. Desv. ; Ephydra longipeivtis, Meigen. 



The larvae live in the urine in privies. Several authors state they have found 

 them in fresh faeces or in vomited matter. Pruvot states that they continue for three 

 days in the stomach of rats into which they have been intentionally introduced. 

 (Pruvot, G., " Contrib. k 1'etude des larves de dipt, trouv. dans le corps humain," 

 These de Par., 1882; Chatin, J., in Comp. rend. Soc. de Biol., Paris, 1888 [8], v, 

 p. 396 ; Roger, H., ibid., 1851 [i], iii, pp. 88, etc.) 



Homalomyia canicularis, L., etc. 



Homalomyia vianicata, Meig., live as larvae in decomposing vegetable matter or 

 in cultivated vegetables (cabbage) ; they are easily recognizable by their plumed 

 bristles, which are situated laterally on the body segments. They obtain access 

 fairly often to the human intestine and give rise to very uncomfortable symptoms. 

 Cases have been recorded from Germany, Austria, France, England, North 

 America (Wacker, in Artzl. Intelligenzbl., 1883, xxx, p. 109; Florentin, in Compt. 

 rend. Soc. de Biol., Paris, 1904, Ivi, p. 525; and other authors). 



The larvae of an allied genus (Anthomyia), which, however, does not possess 

 plumed bristles, has been found in the external auditory meatus of a man (A.pluvialis, 

 according to Danthon). 



[//. canicularis is common to Europe and North America, and is an'abundant 

 house-fly. It is the small house-fly so often seen on windows. Besides living on 

 vegetable matter, they have also been found in the nests of the humble bee. Larvae 

 of this species (fig. 405) were sent to the British Museum, taken from the faeces o 



