HOUSE FLIES. 
INTRODUCTION. 
There are several species of flies which are commonly found in 
houses, although but one of these should be called the house fly proper. 
This is the Musca domestica L. (fig. 1) and is a medium-sized, grayish 
fly, with its mouth parts spread out at the tip for sucking up liquid 
substances. It is found in nearly all parts of the world. On account 
of the conformation of its mouth parts, the house fly can not bite, 
yet no impression is stronger in the minds of most people than that 
this insect does occasionally bite. This impression is due to the- 
Fic. 1.—The common house fly ( Musca domestica): Puparium at left; adult next; larva and 
enlarged parts at right. Allenlarged. (Author’s illustration.) 
frequent occurrence in houses of another fly (Stomozys calcitrans L.) 
(fig. 2), which is called the stable fly, and which, while closely resem- 
bling the house fly (so closely, in fact, as to deceive anyone but an 
entomologist), differs from it in the important particular 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 North- 
eastern States. It breeds in horse manure, cow manure, and in warm 
decaying vegetation like old straw and grass heaps. 
A third species, commonly called the cluster fly (Pollenia rudis 
Fab.), is a very frequent visitant of houses, particularly in the spring 
and fall. This fly is somewhat larger than the house fly, with a dark- 
colored, smooth abdomen and a sprinkling of yellowish hairs. It is 
not so active as the house fly and, particularly in the fall, is very 
459 
5 
