.506 



OTHER liLOOD-SUCKING FLIES 



Fig. 241. Eggs of stable-fly, 



Stomoxys calcitran.<>. X 20. Note 



eggs natural size in upper corner. 

 (After Newstead.) 



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 luimher 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 hou.sefly, 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 

 pupate. The pupae (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 family Muscidae which sometimes 

 bite man, but none of tluMu arc habitual 

 feeders on human blood, and the^-are hardly 

 worthy of special consideration. They all 

 resemble Stomoxya in general appearance, 

 though .some, notably the common hornfly, 

 Hoemalobia 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 njorc than in the ca.se of the stable-flies. 



Fig. 242. Larva (.1) 



and pupa (B) of stahlc- 



i\y, Stomoxys calcitratis. 



X 4. (After Newstead.) 



