INSECTS 357 



into a sort of raft. The larvce which hatch out from them 

 (fig. 209) look something like little red worms with large heads, 

 and they possess a special breathing arrangement in the form of 

 two tubes, each with a stigma at its tip, projecting from the hinder 

 end of the body. The favourite position of the larva is suspended 

 head downwards close to the surface, with the ends of these 

 tubes just projecting above water, and so enabling breathing to 



Fig. aog. — Larva of Common Gnat {Culex pipiens), greatly enlarged 



be carried on. After several moults, the larva becomes a pupa, 

 at the front end of which the wings, legs, and antennae of the 

 adult can be dimly made out under the skin. From each side 

 of the thorax a breathing-tube projects, and these are used like 

 those of the larva, except that owing to their position the animal 

 is suspended tail downwards. The pupa is active, and swims 

 by jerking its tail. Examination from time to time of almost 

 any old rain-water butt will enable one to trace the successive 

 stages of the life-history of the Gnat, the final one of which is 

 reached by the splitting of the pupal skin down the middle of 

 the back, making a rent from which the adult Gnat makes 

 its exit, being floated up meanwhile by the buoyancy of its 

 investments. 



Midges resemble Gnats in many particulars, and pass through 

 a somewhat similar life-history; but they are much smaller, and 

 it is only the females of some species which possess mouth-parts 

 adapted for blood-sucking. The small black Midge {Ceratopogon) 

 which is so troublesome in the summer months is one of these 

 forms. The Plumed Midge {Chironomus plumosus), of which 

 hosts may be seen dancing together any summer evening, is a 

 well-known species, distinguished by the great beauty of the 

 antennae in the male. 



