524 



FLY MAGGOTS AM) MVIASJS 



and mostly without any serious consequences " Banks gives the 

 following quotation from Walsh, — " Taking everything into con- 

 sideration, we doul)t whether, out of 10.000 cases where the larvae 

 of two- winged flies have existed in considerable numliers in the 

 human intestines, more than one single case has been recorded 

 in print by competent entomological authority for the edification 

 of the world." 



Botflies. — There are some flies of the botffy family, (Estridce, 

 which as larvse habitually parasitize the digestive tracts of horses 

 and other domesticated animals, and are especially adapted in 



habits and structure for such a larval life. 

 They occasional!}^, though rarely, occur in 

 man. The horse botfly, Gastrophilus eqtd, 

 for instance, laj's its eggs (Fig. 252) on the 

 haii-s of horses in spots where the\' are likely 

 to be licked. The moisture and rubbing 

 of the horse's tongue cause the eggs to 

 hatch at once, and the new larva?, adhering 

 to tlu> tongue, make their way to the 

 stomach and intestine where they attach 

 themselves and develop to full-grown spiny 

 larva% three-quarters of an inch in length. 

 In the following spring the larva' let go their 

 hold, pass out with the faeces of their host 

 hors7* botfly, "casiro- iuid pupate ill the ground. 01iviousl\- it 

 philus equi, attached could be onlv bv a series of unusual cir- 



tohair; nr., groove for .1 ., /i 1 , 1 • 



cementinKtohair; op., cumstances tfiat these larvaB could gain access 

 opcrcuimii. (Aft.T fo |]j(, human stomach, yet a number of cases 



have been recorded. 

 Fannia Larvae. — A much more common occurrence in man 

 is infection of the intestine with larva? of various species of house- 

 frequenting flies, especially the lesser housefly, Fonnia canicu- 

 laris, and the latrine fly, F. scalaris. The former species is very 

 common in houses both in l^uiope and America. It elo.sely 

 resembles the housefly but is smaller, aii<l appears earlier in the 

 spring. The peculiar manner of (light, a su<lden dart followetl by 

 a hovering, is very characteristic and a good means of identifica- 

 tion. This fly is freciuently ob.seived hovering about chandeliers 

 hanging near ilir center of I'ooms. The eggs arc oval, white 

 oltjects and are laid in decaying vegetable' and animal matti'r 



Fig, 252. Egg of 



