LIFE-HISTORY OF CHIRONOMUS 253 



of species, on the assumption that they all breed true, 

 and it may be that he is right. But until we know 

 the life-histories of the spring and autumn broods of 

 the same gnat races, there is a possibility that seasonal 

 forms of the same species may occur, and that these 

 may have been regarded as of specific instead of 

 varietal value. 



The harlequin fly (Chironomus) is one of the 

 commonest insects that are mistaken for true gnats. 

 It possesses a form similar to that of Culex, and is 

 found in like places under similar conditions, but it 

 can be recognised by the entire absence of a proboscis. 

 It can neither pierce nor suck, and in all probability 

 does not feed. 



The eggs of Chironomus are laid in gelatinous 

 strings about an inch long, moored to the banks of 

 streams and the margins of troughs. The jelly is 

 traversed by twisted fibres about which the hundreds 

 of eggs are arranged spirally. These egg-ropes are 

 an interesting adaptation to aquatic conditions. The 

 strings moor them elastically. The mucilage protects 

 the eggs from predaceous and insidious foes. It raises 

 them to the influence of light, heat, and air, and it 

 enables the eggs to be spaced out without over- 

 crowding. Incidentally this transparent envelope 

 permits direct observation of the development, as 

 Professor Miall's books have so fully shown. 



In a few clays — three to six, according to the 

 higher or lower temperature — the larvae hatch out of 

 these eggs. They are colourless vermiform organisms, 



