506 



OTHER BLOOD-SUCKING FLIES 



posited, sometimes deep in the decajdng material selected, in 



small batches of from two to half a dozen, until from 25 to 50 or 



more are laid; there are a number of such depositions made by a 



single fly during her life. The eggs hatch in from two to five 



days, usually three, into whitish, 

 almost transparent footless mag- 

 gots (Fig. 242A) very similar to 

 those of the housefly, but easily 

 distinguishable by the position of 

 the posterior stigmal plates (see 

 Fig. 243). The larvae mature in a 

 minimmn of from 12 days to over 

 two months, usually in about 15 to 

 20 days, and crawl into drier por- 

 tions of the breeding material to 

 pupate. The pupse (Fig. 242B) are 

 olive-shaped, chestnut-colored ob- 

 jects, one-fourth of an inch in 



length. With favorable temperatures the adult fly emerges in 



from six to ten days, but this period may be much prolonged 



by cold weather. The shortest time in which 



a stable-fly may develop from the time of 



egg-laying is about three weeks, and this is 



extended under conditions which are not 



ideal. According to Herms' experiments, 



the average length of life of stable-flies is 



about 20 days. They sometimes live several 



months, however. 



There are several other genera and species 



of the famfly Muscidae which sometimes 



bite man, but none of them are habitual 



feeders on human blood, and they are hardly 



Fig. 241. Eggs of stable-fly, 

 Stomoxys calcitrans. X 20. Note 

 eggs natural size in upper corner. 

 (After Newstead.) 



worthy of special consideration. 



Fig. 242. Larva U) 



They all and pupa (B) of stable- 



resemble Stomoxys in general appearance, ^^' ^'""^"^y^ caidtrans. 



° 1^X4- (After Newstead.) 



though some, notably the common hornfly, 

 Hoematobia serrata (or Lyperosia irritans) , are much smaDer . Their 

 Ufe histories are in general like that of Stomoxys, though there is 

 some variation as regards choice of breeding places. Manure of 

 various kinds is selected by some species, as it is by the house- 

 fly, much more than in the case of the stable-flies. 



