9 FARMERS’ BULLETIN 679. 
to the frequent occurrence in houses of another fly (Stomozxys cal- 
citrans Li.) (fig. 2), which is called the stable fly, and which, while 
closely resembling the house fly (so closely, in fact, as to deceive any- 
one but an entomologist), differs from it in the important particular 
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Fic, 2.—The stable fly or biting house fly (Stomowys calcilrans) : Adult, larva, 
puparium, and details. All enlarged. (Author's illustration.) 
that its mouth parts are formed for piercing the skin. It is perhaps 
second in point of abundance to the house fly in most portions of the 
Northeastern States. It breeds in horse manure, cow manure, and in 
warm, decaying vegetation, like old straw and grass heaps. 
Fie. 3.—A stable fiy (Muscina stabulans) : Adult, larva, and details. All en- 
larged. (Author’s illustration.) 
A third species, commonly called the cluster fly (Pollenia rudis 
Fab.), 1s a very frequent visitant of houses, particularly in the spring 
and fall. This fly is somewhat larger than the house fly, with a 
smooth, dark-colored abdomen and a sprinkling of yellowish hairs. 
