608 DIPTERA. 



though it approaches the latter in its structure, and in its 

 sluggish habits. The larvae or maggots, though not yet 

 discovered, undoubtedly live in the ground, or in decayed 

 vegetable substances, like those of the horse-flies and other 

 predatory insects ; for Mr. Gosse found one of his specimens, 

 on the grass, in the act of emerging from the pupa-skin. 

 He has also figured * the pupa, which is of a chestnut-brown 

 color, and has transverse rows of spines on the abdominal 

 rings. 



Most of the soldier-flies (Stratiomyad^e) are armed with 

 two thorns or sharp spines on the hinder part of the thorax. 

 They form the first family of the flies that undergo their 

 transformations within the hardened skin of the larva, which 

 is not thrown off till they break through it to come out in the 

 winged state. Their proboscis contains, at most, only four 

 bristles, is not fitted for piercing, but ends with large fleshy 

 lips, by means whereof these flies suck the sweet juices of 

 flowers. Most of them are found in wet places, where their 

 larvae live; some of the latter being provided with a tube, 

 in the hinder extremity, which they thrust out of the water 

 in order to breathe. The skin of these larvae is merely 

 shortened a little, without wholly losing its former shape, 

 when the enclosed insects change to pupae ; thereby showing 

 that this family is truly intermediate between the preceding 

 flies, which cast off their larva-skins, and those which retain 

 them, and take an oblong oval shape, when they become 

 pupae. Some of the soldier-flies QStratyomys} have a broad 

 oval body, ornamented with yellow triangles or crescents 

 on each side of the back, and their antennae are somewhat 

 like those of Midas and of the gad-flies ; others (Sargus) 

 are slender, often of a brilliant brassy-green color, with a 

 bristle on the tip of their antennae. The maggots of the 

 latter live in rich mould. 



The Syrphians (Syrphid^e) have a fleshy, large-lipped 

 proboscis, elbowed near the base, and enclosing only four 



* Canadian Naturalist, p. 199. 



