412 



NATURAL HISTORY OF ARTHROPODS. 



Fig, 615. — ^ImuLlum 

 molestum, black fly, 

 enlarged. 



in length ; after a considerable beating they flew away. Several other instances are 

 known even in quantities much larger than this ; in one a swarm attached itself to the 

 handle of an iron pot." 



S. molestum is the species most common in northern New England, and one that 

 causes much annoyance to man and beast in the mountainous regions. They have a 

 black body, with transparent wings, and are hence called "black- 

 flies." A southern species resembling them, but smaller, is very 

 annoying to fowls, especially turkeys, whence they are called "tur- 

 key gnats." They attack the turkeys in the bare regions about 

 the head, in the ears, eyes, etc., often destroying them in numbers. 

 In the BiBioxiD^, which includes about three hundred de- 

 scribed species, there are three ocelli, there is no transverse 

 suture to the thorax, and the prothorax is much developed. The 

 wings are without a discal cell, and the coxae are not prolonged. 

 The larvae are cylindrical, footless, with transverse rows of bristles, the head often 

 with eyes. They feed on excremental or vegetable substances, especially on the roots 

 of grass, whole patches of which they are said to destroy. The pupae are inactive, 

 mostly free, remaining in excavated, smooth, oval cavities near the surface of the ground, 

 which the larvae have prepared before undergoing their metamorphosis, and where the 

 pupas remain till they are ready to emerge in the perfect state. The males, which are 

 fewer in number than the females, make their appearance several days before their 

 mates ; in some species the males differ markedly in coloration from the females, so 

 that they might be considered as different. 



The adult flies are most usually seen in early spring about gardens, on flowers, etc. 

 Jiibio albipemiis, our most common species, is black ^\ith white wings, and, with other 

 species of the same genus, shows a conspicuous, stout spur on the front tibiae. They 

 are found in abundance on willows in early spring, but there is also another brood 

 later in the season. Several other species of this genus that are commonly observed 

 are of a deep red color with black wings. The males will be distinguished by their 

 very large eyes, comprising nearly the whole head, and thickly covered with hair. 

 Most of the species are dull and sluggish, and fly heavily. 



The family Chieonomid^ comprises a large number of very delicate flies which, 

 owing to their delicacy and simplicity of structure, have not been much studied by 

 entomologists. Not more than eight hundred species are known. They have no 

 ocelli, the thorax has no transverse suture, the costal vein ends near 

 the tip of the wing, and docs not continue around the posterior 

 part ; this last character will distinguish them from the mosquitoes, 

 which they much resemble. The antennae are very strongly plumose, 

 especially in the males, where they form two dense brushes ; in the 

 female they are usually shorter, less densely plumose, and composed 

 of fewer joints. The larvae are soft-skinned, worm-like, often blood- 

 red in color, and usually aquatic, as are also the active pupae, though 

 some live in decomposing vegetable matter or in the earth. But 

 few of the adult flies can bite like the mosquito, and most of them 

 are harmless or beneficial. Every one has noticed them in abund- 

 ance in early sj)ring before the snow is o£E the ground. They will 

 collect in large swarms, dancing in the air. Indeed, over meadows in the Rooky 

 Mountains the writer has seen them rise up at nightfall in the most incredible num- 



FiG. 616. — Pupa and 

 anal foot of Chir- 

 onomus. 



