VII 



BIBIONIDAE SIMULIIDAE 



477 



be spiracles. The food of Seatopsc in the larval state is 

 principally vegetable. The larva of Scatopse changes to a 

 pupa inside the larval p 



skin ; the pupa is pro- 

 vided on the thorax with 

 two branched respiratory 



processes that project 

 outside the larval skin. 1 

 Lucas has given an in- 

 teresting account of the 

 occurrence of the larva 

 oiBiliio marci in enorm- 

 ous numbers at Paris ; 

 they lived together in 

 masses, there being ap- 

 parently some sort of FlG - 226. Portion of integument of Bibio sp. Cam- 

 bridge, u, Intersegmental processes ; s, spiracle. 



connection between the 



individuals. 2 In the following year the fly was almost equally 



abundant. 



Owing to the great numbers in which the species of Bibionidae 

 sometimes appear, these Insects have been supposed to be very 

 injurious. Careful inquiry has, however, generally exculpated 

 them as doers of any serious injury, though Dilophus febrilis a 

 so-called fever-fly appears to be really injurious in this country 

 when it multiplies excessively, by eating the roots of the hop- 

 plant. 



Fam. 11. Simuliidae (Sand-flics, Buffalo-gnats). Small obese 

 flies u'ith It limped lack, rather short legs and Inroad v:in<js, with short, 

 straight n n/i'n ne destitute of setae; proboscis not projecting. 

 There is only one genus, Simulium, of this family, but it is very 

 widely spread, and will probably prove to be nearly cosmo- 

 politan. Some of the species are notorious from their blood-suck- 

 ing habits, and in certain seasons multiply to an enormous extent, 

 alight in thousands on cattle, and induce a disease that produces 

 death in a few hours ; it is thought as the result of an instilled 

 poison. S. columbaczense has occasioned great losses amongst 

 the herds near the Danube; in North America the Buffalo- and 

 Turkey-gnats attack a variety of mammals and birds. In Britain 



1 IVrris, in Ann. Soc. ent. France (2) v. 1847, p. 37, pi. i. 

 2 Ann. Sue. ent. France (5) i. 1871, Bull. p. Ixvii. 



