THE AMERICAN ENTOMOLOGIST. 



139 



We will now give such recorded cases as we 

 have been able to glean, of flie occnrreucc of the 

 larvaj of Flat-flies or other Two-winged flies in 

 the human bowels, whether in this country or 

 in Europe. In Europe tiiere are two species in 

 particular, respecting which such facts have been 

 recorded, namely, the I'uppy Flat-fly (Horn, 

 canicularis, Meig.) and the Ladder-fly {Horn, 

 scalaris, Meig.) The larvie of the Ibrmer arc 

 well known to occur normally in rotten vege- 

 tables and decayed cheese, and the fly itself, 

 from its being often noticed in houses, has been 

 sometimes called "The Lesser lloiise-fly," 

 though from the true House-fly {Musca domes- 

 tica) it differs by very conspicuous structural 

 characters. The larvoe of the Ladder Flat-fly 

 are met with in human excrements, and from 

 their being often found in the putrid contents 

 of privies, the fly itself has fretjuently been 

 characterized as'" the Privy-fly." 



The Kev. L. .Tenyns, of Cambridgeshire in 

 England, published 30 or 40 years ago a very 

 detailed account of the larviB of the Puppy Flat- 

 fly having been discharged from the intestines 

 of a clergymen.* Fallen records a similar case, 

 though he thought that the larvic might possibly 

 belong to an allied species. f On the other 

 hand, Westwood tells us that in two different 

 medical works, one in the German and the other 

 in the English language, the larvas of the Ladder 

 Flat-fly are stated to have been found in the 

 human body. J Several other European cases 

 are on record, where the larvae of Two-winged 

 flies have either been evacuated from the anus 

 or vomited from the mouth ; but in most of them 

 the genus to which they belonged cannot be 

 accurately determined. In the United States, 

 Dr. Leidy, as quoted by Dr. Packard, § has rc- 



tarina npi 

 tl e Bcffcne 

 I access, 1 1 



corded a case where numerous larva;, supposed 

 to be those of some Flower-fly {Anthomyia) , 

 were given to him for examination by a phy- 

 sician, who had obtained them from his own 

 person. This physician, it is added, had been 

 seized with all the symptoms of cholera morbus, 

 and in his discharges he had detected numerous 

 specimens of this, to him, unknown pai-asite. 

 The above circumstances took place in the latter 

 part of summer, and it was suspected that the 

 larva; had been swallowed along with some cold 

 boiled vegetables . The very same kind of larva 

 had been previously observed by Dr. Leidy in 

 another such case, which was likewise accom- 

 panied by the ordinary phenomena of cholera 

 morbus. On referring to the description of 

 these larvas published by Dr. Leidy, we flnd 

 that they are represented as having very nearly 

 the same kind of lateral gills as those which we 

 have figured above ; and they must consequently 

 appertain to the Flat-flies and not (o the Flower- 

 flies (Anthomyia), as was erroneously supposed 

 by the author of the description. 



Of course, every one must perceive at once 

 that a larvj furnished with gills, and jiot liable 

 to drown when immersed in fluid or semi-fluid 

 matter, would stand a much better chance to 

 live and flourish in the human stomach, than a 

 larva that breathes the air much in the same man- 

 ner as we ourselves do. But there is authentic 

 evidence that larvie which breathe through spi- 

 racles in the ordinary manner, and not through 

 lateral gills, have been voided either upwards or 

 downwards from the human body. For Dr. Leidy 

 has further reported* a case where a number of 

 specimens, which appeared to be larva; of the 

 Blue-bottle Fly, were given him by a physician 

 as having been vomited from the stomach of a 

 cl il 1; and Baron Osten Sacken has kindly in- 

 1 im d us, that in the winter of 1868-9 some 

 m )uth Dipterous larvas were handed over to 

 1 jni by a New York physician as having been 

 \ 1 kd in the excrenieut of a child; and that 

 tl ni one of them he reared what was apparently 

 I lecimen of the common House-fly (Musca 

 loi it rftcrt) . So far as we are aware, this is the 

 inh case recorded by authors, where larvffi dis- 

 1 1 „ ed from the human body have been actually 

 1 1 1 to the perfect Fly state. 



Ihe question naturally recurs here — "How 

 in all these numerous instances did so many 

 Imse find their way into the human body?" 

 Two opinions, as the reader will have noticed, 

 hn( been expressed above as to this knotty 

 1 loblem ; one by Dr. Leidy's friend, that all the 



*1 o:. Ac. Nat. Sc. I'hilnrI , Issa^, l!ioli)gic:il Ufpnvtiiicnt, 



