Stomoxys calcitrans, the Stable-fly 



161 



fact, the true house-flies never bite, for their mouth-parts are not 

 fitted for piercing. The basis of the misconception is the fact that a 

 true biting fly, Stomoxys calcitrans (fig. no), closely resembling the 

 house-fly, is frequently found in houses and may be driven in in 

 greater numbers by muggy weather. From its usual habitat this 

 fly is known as the "stable-fly" or, sometimes as the "biting house- 

 fly." 



Stomoxys calcitrans may be separated from the house-fly by the use 

 of the key on p. 145. It may be more fully characterized as follows: 



The eyes of the male are separated by a distance equal to one- 

 fourth of the diameter of the head, in the female by one-third. The 



110. Stomoxys calcitrans; adult, larva, puparium and details, (x 5). After Howard. 



frontal stripe is black, the cheeks and margins of the orbits silvery- 

 white. The antennae are black, the arista feathered on the upper 

 side only. The proboscis is black, slender, fitted for piercing and 

 projects forward in front of the head. The thorax is grayish, marked 

 by four conspicuous, more or less complete black longitudinal stripes ; 

 the scutellum is paler; the macrochaetae are black. The abdomen is 

 gray, dorsally with three brown spots on the second and third seg- 

 ments and a median spot on the fourth. These spots are more 

 pronounced in the female. The legs are black, the pulvilli distinct. 

 The wings are hyaline, the vein Mi+ 2 less sharply curved than in 

 the house-fly, the apical cell being thus more widely open (cf. fig. 

 no). Length 7 mm. 



This fly is widely distributed, being found the world over. It was 

 probably introduced into the United States, but has spread to all 



