The Fly 9 



depth of winter. Some of these unseasonable examples 

 have lately emerged from the pupa- skin ; others have 

 lingered on from the previous warm season. An insect 

 which has been unable to mate sometimes survives its 

 companions for a long time. 



The fly of the blood-worm is a gnat-like creature, The %. 

 which is often seen in summer on the window-pane, or 

 hovering in swarms over streams and pools. When at 

 rest, it usually stretches out its fore-legs, raising them 

 altogether from the ground ^ Unlike the gnat, it has 

 no biting or piercing organs, and is quite harmless. The 

 mouth is almost closed, and feeding seems to be im- 

 possible. The head is furnished with great compound 

 eyes, and in the male, with large plumed antennae. The 

 female has simpler antennae, and the eyes are not so 

 large as in the male. Swarms of flies, composed almost 

 entirely of males, dance in the air of an evening. Now 

 and then a pair falls towards the ground ; the male soon 

 rejoins the swarm, but the female flies off'. (See addi- 

 tional note, p. 183.) 



The fertile female skims over the surface of the water, Egg-iaying 

 touching it lightly from time to time with her legs. 

 This is preliminary to the laying of the eggs, which com- 

 monly takes place in the late evening or early morning. 

 She settles at last on the margin of a pool or stream, and 

 brings the tip of the abdomen close to the surface of the 

 water. A dark gelatinous mass, consisting of eggs thinly 

 covered with mucilage, is then protruded until it touches 

 the water, when it at once begins to swell up. After all 

 the eggs are passed out, the whole mass, which forms 

 a gelatinous cylinder, is secured by the female to some 

 fixed object close to the water's edge. The attachment 

 varies according to the species of the fly, but often takes 



' Gnats may be seen to lift the liind legs, and wave them slowly about, 

 as if to explore. 



