20 AMERICAN BLACK FLIES OR BUFFALO GNATS. 



found in this stage in America. It occurs in the early months of the 

 year — is stated by some observers to hibernate in this stage — and 

 pupates at the end of April, the imago emerging in about 10 days 

 after pupation takes place. 



Pupa. — This species may be known in the pupal stage by the very 

 large number of respiratory filaments (PI. IV, fig. 5). These num- 

 ber as high as GO in some cases, but as is generally the case where 

 there is a multiplicity of branches there is a greater tendency to 

 variation in number than with the species which have only a few 

 filaments. No distinct cocoon is formed by this species. 



This fly is reported to be a very persistent biter and does not con- 

 fine its attentions to cattle, but attacks human beings as well. 



I have only one poorly preserved European specimen of hirtipes 

 before me and can not find any characters to separate it from the 

 American species. They may be identical, but only a knowledge of 

 the early stages of both can definitely decide this. 



The species figured in Bulletin 159,^ Kentucky Agricultural Ex- 

 periment Station, is quite evidently hirtipes and not peeuarum Riley. 



There are several specimens in collections from the White Moun- 

 tains and also some from British Columbia which have the legs 

 yellow. These may belong to a different species, but I can not find 

 any distinguishing characters in the specimens other than this, which 

 I consider is too prone to variation to prove reliable. 



Prosimulium mutatum, new species. 



Female. — Black-gi'ay, subopaque. Only the prescutum, posterior 

 portions of pleurte, and legs more or less yellowish. Mesonotum 

 without distinct pollinosity, and unstriped. Wings grayish, veins 

 brown. Halteres brown. 



Frons gray-dusted, narrow, slightly divergent-sided, occupying 

 about one-fifth the width of head at upper angle of eyes, a distinct, 

 central, longitudinal depression over antennae, surface hairs pale, 

 sparse ; face colored as is frons, a little longer than wide, and as wide 

 as frons at upper angle, surface hairs pale; antenna^ with the basal 

 joints not distinctly paler than remainder; hairs on palpi dark; pro- 

 boscis short ; postocular cilia pale, with a few longer black hairs inter- 

 mixed. Mesonotum with sparse, rather widely separated, yellow, 

 hair-like pilosity; posterior fourth of scutum with a few upright 

 black hairs; pleural tuft pale, long, confined to upper fourth; scu- 

 tellum with pale upright pilosity and upright brown hairs. Abdo- 

 men with pale basal fringe, and scattered pale surface hairs, which 

 are more numerous on lateral margins and apical segments. Legs 

 with pale pilosity and dark, longer, upright dorsal hairs; fore tarsi 



1 Bui. 159, Ky. Agr. Exp. Sta., fig. 4, p. 18 ; flg. 5, p. 20 ; fig. 6, p. 21, 1012. 



