COMMON FLIES AND HOW TO TELL THEM APART 143 



2. Body same as above species, stigmal plate with three S-shaped 

 slits (figs. 23, 24). Stomoxyn calcitrans. 



B. Two great mouth-hooks; slits m stigmal plate not winding. 



1. Body slightly rounded at rear end, faintly spined and with three 

 short, pointed slits in stigmal plate (figs. 25, 26). 



Muscina stabvlans. 



Fig. 14. — ^Larva of the little house fly, Pannia canicularis. Greatly enlarged. (Howard 

 and Pierce, drawing by Bradford.) 



Fig. 15. — ^Dorsal view of eighth abdominal 

 segment of the larva of Fannia came- 

 ularis. Very highly magnified. (Draw- 

 ing by Bradford.) 



Fig. 16. — Ventral view of terminal seg- 

 ments of Pannia canicularis; the ninth 

 and tenth segments are comprised in 

 the small zone around the anus. Very 

 highly magnified. (Drawing by Brad- 

 ford.) 



2. Stigmal plates wide apart, each with three straight slits nearly 

 transverse to the body and a distinct button (figs. 27, 28). 



Calliphora erythrocephala. Calliphora vomitoria. 



3. Stigmal plates about half their diameter apart, each with three 

 straight slits directed somewhat downward (fig. 31). 



Lucilia sericata. 



4. Stigmal plates less than their own diameter apart, each with 

 three straight slits pointed downward; no button (figs. 29, 30). 



Chrysomya macellaria. 



