66 AMERICAN BLACK FLIES OR BUFFALO GNATS. 



have the dorso-lateral stripes generally discontinued before the an- 

 terior margin and not outwardly curved, as well as the central line 

 extremely narrow ; the pilosity over the whole insect is longer than 

 in forhesi and conspicuously so on the abdomen ; the marking on the 

 abdomen is usually confined to a series of spots, one on each side of 

 the first four segments exclusive of the basal scale. The species is 

 also noticeably larger than either forhesi or meridionale, being 3^ 

 mm. in length. 



For description of larva and pupa see Hart's paper above men- 

 tioned. 



It is possible that the larger specimens mentioned as in the U. S. 

 National Museum collection under meridionale are really this species, 

 but I have no means of determining that question at present. 



So far as my material permits me to judge, johannseni occurs at 

 Havana, 111., till the end of May, when its place is taken by forhesi, 

 which is equally abundant. 



Simulium meridionale Riley and its allies. 



The three species which I at present recognize as belonging to this 

 group are ineridionale Riley, johannseni Hart, and forhesi new 

 species. 



The pupal stages of these three species, which are very closely 

 allied in the adult stage, are very distinct and may be readily sep- 

 arated from one another by the number of pupal respiratory filaments. 

 In johannseni these are 4 in number, in meridionale 6, and in forhesi 

 generally 24 or 25, although, as is the case when a large number of 

 filaments are present, there may be a slight variation in the total 

 number in individual specimens. J ohannseni is the only species 

 which I have seen with four pupal filaments, although hracteatum has 

 been recorded by Strickland as possessing this number also. I have 

 not seen Strickland's material, so can not confirm the identification. 



The adult females of this group of species may be readily distin- 

 guished from other North American forms by their possession of the 

 following combination of characters: Scutum with three vitta3, the 

 submedian pair curved; the pilosity hairlike on scutum; abdomen 

 more or less distinctly spotted on middle of each dorsal segment ; legs 

 generally almost unicolorous, rarely distinctly bicolored (in alcoholic 

 specimens this bicoloring is conspicuous in the case of johannseni) ; 

 claws bifid. The males are not so readily separated, but I have in- 

 serted them in my synoptic key, by means of which I believe they may 

 be readily located. 



From the data gathered in the field work on this group in the 

 Illinois River region, near Havana, it is evident that johannseni, 

 although a pest owing to the great numbers in which it occurs, does 



