FIELD BOOK OF INSECTS. 



Fifteen genera, including a total of twenty species, have 

 been found within fifty miles of New York City and are so 

 widely distributed that they are to be looked for throughout 

 the United States and, indeed, the whole world. Still 

 another eastern genus (Protocalliphora) has the disagree- 

 able habit of breeding in nestling birds, causing their 

 death. It is hoped that the following key, taken in connec- 

 tion with the descriptions and figures, will enable the 

 careful student to identify the common species. 



1. Proboscis long, slender, horny, adapted for piercing . . 2. 

 Proboscis not so, having fleshy labellag ("lips") at 



the tip 3. 



2. Dark ash-gray, with a faint tinge of yellow; thorax 

 and abdomen with no distinct markings; not larger 

 than Musca domestica; palpi nearly as long as the 

 proboscis Hcematobia irritans. 



Palpi much shorter than the proboscis 



Stomoxys calcitrans. 



3. Thorax with a fairly distinct median dark stripe. 

 (When the stripe is very faint try 15) 4. 



Thorax with the median stripe light, or thorax with 

 no distinct stripes 6. 



4. Abdomen non-metallic in color, spotted or macu- 

 lated Graphomyia maculata. 



Abdomen metallic blue or green; not maculated 5. 



5. Face light yellow 7 ; thorax metallic, stripes very 

 distinct Chrysomyia macellaria. 



Face reddish-brown; thorax non-metallic; stripes 

 rather indistinct Cynomyia cadaverina. 



6. Abdomen opaque brown, a pair of triangular black 

 spots on each of the second and third abdominal segments 

 of the male. These spots are faint or wanting in the 

 female Myospila meditabunda. 



Abdomen not marked in this way 7. 



7. The 4th longitudinal vein slightly bent 8. 



The 4th longitudinal vein sharply bent 10. 



8. First posterior cell narrowly contracted at the margin; 

 bluish-black, shining; the tip of the scutellum not reddish; 

 the median light stripe on the thorax more distinct than 

 the others Morellia micans. 



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