146 Arthropods as Simple Carriers of Disease 



arranged in a longitudinal series and in addition two pairs 

 of series of smaller processes (fig. 100) F. canicularis 

 bb. Male with blackish abdomen, middle tibia with a tubercle 

 beyond the middle. The larva with spiniferous appen- 

 dages of which the dorsal and ventral series are short, the 

 lateral series long and feathered (fig. 101). . . .F. scalaris 

 aa. Apical cell (R) of the wing more or less narrowed in the 

 margin; i. e., the bounding veins more or less converging 

 (fig. 108). 



b. The mouth-parts produced and pointed, fitted for piercing. 

 c. Palpi much shorter than the proboscis ; a brownish gray 

 fly, its thorax with three rather broad whitish stripes; 

 on each border of the middle stripe and on the mesal 

 borders of the lateral stripes is a blackish brown line. 

 Abdomen yellowish brown; on the second, third and 

 fourth segments are three brown spots which may be 

 faint or even absent. The larvae live in dung. The 



stable-fly (fig. no) Stomoxys calcitrans 



cc. Palpi nearly as long as the proboscis. Smaller species 

 than the house-fly. The horn-fly (fig. 167) 



Hamatobia irritans 



bb. Mouth-parts blunt, fitted for lapping. 



c. Thorax, particularly on the sides and near the base of the 



wings with soft golden yellow hairs among the bristles. 



This fly is often found in the house in very early spring 



or even in the winter. The cluster-fly, Pollenia rudis 



cc. Thorax without golden yellow hairs among the bristles. 



d. The last segment of the vein M wHh an abrupt 



angle, (fig. 108). The larvae live in manure, 



etc House-fly, Musca domestica 



dd. The last segment of vein M with a broad, gentle 



curve (fig. 102). 



e. Eyes microscopically hairy; each abdominal 



segment with two spots. Larvae in dung. 



Myiospila meditabunda 



ee. Eyes bare; abdomen gray and brown marbled. 



Muscina 

 f . With black legs and palpi. M. assimilis 



