Diptera: Nemocera vera, N. anomala and Eremochacta. 453 



cilia; tegulae rudimentary. The color of the eyes in life is reddish. 

 The female differs very much from the male in the color of the body 

 and its pubescence; the eyes are reniform, or rather oval with an 

 abrupt excision on the inner side, separated by a broad front, 



The habits oi Simulium (comp. p. 444) are the opposite of cre- 

 puscular; they love heat and streng light, and the males disport 

 themselves high in the air in the sunshine. (I have often watched 

 swarms of male Simulhmi dancing about the towers erected on the 

 mountain-tops around Heidelberg; they occur on both sunny and 

 clouded days. The females generally remain in the lower regions, 

 and annoy men and horses.) 



The metamorphoses of Simulium have been often described and 

 are very peculiar. As larvae and pupae live in rapidly running wa- 

 ters, they cannot swim about freely, like most of the larvae of the 

 Nemocera vera, for fear of being carried away; protection against 

 this danger is therefore one of the conditions of their existence, 

 Fastened by their tail-end to stones and aquatic plants, they move 

 from place to place by means of a thoracic pseudopod, always follo- 

 wed by a thread of silk emitted from their mouth; these threads 

 proved very destructive to young trout in the breeding ponds in the 

 State of N. York (compare the Amer. Entomologist and Botanist, 

 Vol. IL p. 227, 1870). The larvae require „a brisk flow of well-ae- 

 „rated water .... There are no externally visible organs of respi- 

 „ration, but the skin is supplied by an abundant network of fine 

 „tracheal branches which take up oxygen from the water .... They 

 „subsist entirely upon microscopic plants and animals. Among these 

 „are great uumbers of Diatoms, and the stomach is usually half- 

 „full of the flinty valves of these microscopic plants." (Miall, Nature 

 Feb. 1892.) The pupae are maintained in position by a semi-oval 

 cocoon fastened under water to a stone or waterweed; the opening 

 of the cocoon is always directed with, and not against the current;i) 

 the pupae breathe by a number of respiratory filaments on each side 

 of the thorax. The wonderful escape of the fly from under water is 

 also described by Prof. Miall (Nature, May 5, 1892). According to 

 Tom ÖS Vary the pupae spend the winter in a state of torpor and 

 come out in the spring (1. c. p. 9). 



This family contains but a Single genus Sim^uliumi) reprosented 

 by rather numerous species in Europe, North- and South-Araerica; 



j) Observation of Dr Edmund Töniösvary in bis pamphlet: Die 

 Kolumbaczer Mücke; 1885. 



•i) Latreille has il Simulium. Meigen, Syst. Beschr., made it 

 Simulia without giving any reason. Macquart, in tbe Dipt. du Nord, 



