506 



OTHER BLOOD-SUCKING FLIES 



posited, sometimes deep in the decaying 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 

 minimum 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 



FIG. 241. Eggs of stable-fly, niinn 4- p ^TV, P nnnJP (Trip- 942T^ nrp 

 Stomoxys calcitrans. X 20. Note Pupate. Ine pup83 ^lg. ZZZti) are 



eggs natural size in upper corner, 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 family Muscidse which sometimes 

 bite man, but none of them are habitual 

 feeders on human blood, and they are hardly 

 worthy of special consideration. They all and"pupa~(B)"of"stabiel 

 resemble Stomoxys in general appearance fly> Stomox y s calcitrant 



, , , X 4. (After Newstead.) 



though some, notably the common hornfly, 

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

 life 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. 



FIG. 242. Larva (A) 



