INSECTA : DIPTERA 



353 



The Imago. 



pair of spines with which it is said to be able to fix itself to 

 floating objects. 



From the pupa emerges a fly with a humped 

 thorax bearing a little horn-like projection behind, 

 and a pair of transparent naked wings which are laid hori- 

 zontally over the body when at rest (Fig. 277). The eggs are 

 laid in star-shaped clusters of a hundred or more amongst 

 the floating vegetation of the pond. 



Most other species of Ceratopogon are not aquatic in the 

 larval state, but are terrestrial, living under the bark of trees. 

 These forms have flies with hairy wings ; many of them are 

 annoying little creatures, with a most irritating sting ; 

 Ceratopogon varius of Scotland is one of these pests. 



Family 3 : Simdliidae (Sand-flies or Bdpfalo-gnats) 



Sand-flies are little, dark-coloured flies with a humped 

 thorax, short straight anten- 

 nae, no projecting proboscis, 

 rather short legs, and broad 

 long wings. 



Fio. 278. — Simulium, the Sand-fly. 



The River Sand-fly (Simuliwm). 



These flies often congregate in numbers 

 on the bushes near a swiftly running stream, 

 feeding, it is said, on the juices of leaves, or 

 on the honey -dew given out by Aphides. 

 The female flies lay their eggs in jelly-like 

 masses attached to the water-plants growing 

 close to the water or at its surface, and soon 

 there will be hundreds of the strange little 

 black larvae clinging to the under side of the 

 leaves wherever the current of water is 

 swiftest. 



The larva has a segmented 

 body which is thinnest in the 

 centre. The swollen hind end bears a median structure 

 VOL. I 2 a 



Fig. 279. 

 «, The eggs of Simu- 

 liv/m on a water- 

 plant. 



