47$ DIPTERA 



CHAP. 



and other parts of the world they do not increase in numbers to 

 an extent sufficient to render them seriously injurious : their bite 

 is however very annoying and irritating to ourselves. In their 

 early stages they are aquatic and require well aerated waters : 

 the larvae hold themselves erect, fixed to a stone or some other 

 object by the posterior extremity, and have on the head some 

 beautiful fringes which are agitated in order to bring food within 

 reach ; the pupae are still more remarkable, each one being 

 placed in a pouch or sort of watch-pocket, from which projects 

 the upper part of the body provided with a pair of filamentous 

 respiratory processes. For an account of the interesting circum- 

 stances connected with the metamorphoses of this species the 

 reader should refer to Professor Miall's book ; and for the life- 

 history of the American Buffalo-gnat to Biley. 1 



Fam. 12. Rhyphidae. This is another of the families that 

 have only two or three genera, and yet are very widely distributed. 

 These little flies are distinguished from other Nemocera Anomala 

 (cf. p. 456) by the presence of a disced cell ; the empodia of the 

 feet are developed as if they were pulvilli, while the true pulvilli 

 remain rudimentary. The larvae are like little worms, being 

 long and cylindric; they are amphipneustic, and have been 

 found in decaying wood, in cow-dung, in rotten fruits, and 

 even in dirty water. The "petite tipule," the metamorphoses of 

 which were described and figured by Reaumur, is believed to 

 be the common Rhyphus fenestralis. 2 R. fenestralis is often 

 found on windows, as its name implies. 



Series 2. Orthorrhapha Brachycera 



Fam. 13. Stratiomyidae. Antennae with three segments 

 and a terminal complex of obscure joints, frequently bearing 

 an arista : tibiae not spined ; wings rather small, the an- 

 terior nervures usually much more strongly marked than those 

 behind. The median cell small, placed near to the middle of the 

 wing. Scutellum frequently spined ; terminal appendages of tli e 

 tarsi small, but pulvilli and a pulvilliform empodium are 



1 Rep. Dep. Agric. Ent. Washington, 1886, p. 492. 



2 Cf. Reaumur, Mem. v. 1740, p. 21 ; and Ferris, Ann. Soc. ent. France (4) x. 

 1870, p. 190. 



