404 INSECTS INJURIOUS TO VEGETATION 



Among our long-legged gnats there is no one more singular in 

 its appearance aul s;racef( 1 m its motions than the Piyrhoptera 

 clavipes^ of Fabricius, or club-footed Ptychoptera. A new 

 genus, called Biitacomorpha, on account of the fancied resem- 

 blance of this insect to the Neuropterous genus Bittacus, has lately 

 been made for its reception, by Mr. Westwood.* This pretty 

 gnat is of a black color, with abroad, white stripe on the face, 

 a short, white hne on the forepart of the thorax, and three broad, 

 white rings on the legs. The sides of the thorax are silvery 

 white, and the hind-body is dusky brown, with a narrow white 

 line on the edges of each of the rings. The head is small, and 

 almost hidden under the thick and hunched thorax ; the antennae 

 are many-jointed, slender, and tapering ; the hind-body is long, 

 narrow, and somewhat flattened ; the legs are very slender next 

 to the body, and increase in thickness towards the end, and the 

 first joint of the feet is swollen, oblong oval, and very downy. 

 The length of the body is about half an inch, and the wings ex- 

 pand nearly three quarters of an inch. It appears in July, and 

 takes wing by day. As it flies slowly along, it seems almost to 

 tread the air, balancing itself horizontally 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-gnat, or Chionea valga. 

 This singular 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 antennae 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 o{ valgn^ 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 



* " Philosophical. Magazine," Vol. VI. p. 281. Lend. 1835. 



