THE THICK-LEGGED SNOW-GNAT. 601 



along, it seems almost to tread the air, balancing itself hori- 

 zontally with its long legs, which are stretched out, like rays, 

 from the sides of its body. 



There are exceptions to almost all general rules. Thus we 

 find, among Dipterous insects, some kinds that never have 

 wings. One of these is the thick-legged snow- 



. . Fig- 260. 



gnat, or Chionea valga 1 (Fig. 260). This singu- 

 lar insect looks more like a spider than a gnat. 

 Its body is rather less than one fourth of an inch 

 long, and is of a brownish yellow or nankin color. 

 The legs are rather paler, and are covered with 

 short hairs. The head is small and hairy. The first two 

 joints of the antennas are thick, the others slender and 

 tapering, and beset with hairs. Although the wings are 

 wanting, there is a pale yellow poiser on each side of the 

 hinder part of the thorax. The hindmost thighs are very 

 thick, and somewhat bowed, in the males, which suggested 

 the name of valga, or bow-legged, given to the insect in my 

 Catalogue. The body of the female ends with a sword- 

 shaped borer, resembling that of a grasshopper. These 

 wingless gnats live on the ground, and the females bore 

 into it to lay their eggs. They are not common here. Mr. 

 Gosse found considerable numbers of them in Canada, 

 crawling on the snow, in pine woods, during the month 

 of March.* 



Travellers and new settlers, in some parts of New Eng- 

 land and Canada, are very much molested by a small gnat, 

 called the black fly (Simulium molestum), swarms of which 

 fill the air during the month of June. Every bite that they 

 make draws blood, and is followed by an inflammation and 



[ i Mr. Walker has described two American species of this singular genus ; one 

 of them, Chionea aspera, seems to be identical with Dr. Harris's C. valga. I do 

 not undertake to decide which name should be preferred. Dr. Harris's has the 

 priority, but the few words he mentions about this insect can hardly be called a 

 description. (Compare Walker's List of Diptera of British Museum, Vol. I. p. 82.) 

 OSTEN SACKEN.] 



* Canadian Natitralist, p. 51. 

 76 



