xxm INSECTA: DIPTERA 347 



Type : The Harlequin-fly (Chironomus). 



The Harlequin-fly is usually mistaken for a gnat, but it is 

 really quite a harmless midge that cannot sting. On the 

 window-pane it can easily 



be distinguished from a rrr_ r^ "* : *** 



gnat by noting its charac- 

 teristic attitude (compare 

 Figs. 268 and 260). Like 

 a gnat, the Harlequin 

 seeks water when about FIG. 269. Chironomus Eggs. 



to lay her eggS. Upper diagram, egg-rope entire ; lower diagram, 



rrn pa- ox a sma ^ pi gce cu t across and drawn to show 



Eggs. . . & the regular arrangement of the eggs. 



are laid in a 



gelatinous rope, sometimes nearly an inch long, which is 

 moored at one end to some object, frequently to the side of 

 the rain-water tub in which the eggs are so often to be found. 



The larvae are bright red in colour, and are 

 The Larvae. , u j r ^ 



usually known as blood-worms. Ihey may be an 



inch long when full grown, and they swim very rapidly in 

 the water, contorting their bodies into loops, and even figures of 

 eight, as they move, and so earning the name of " Harlequins." 

 Although they are very frequently to be seen swimming freely 

 in the water, especially at night, normally they make for 

 themselves little tubes of earth either at the water bottom, 

 or on the side of the vessel they are in, sticking the particles 

 together with a silky secretion from the mouth. In this 

 tube they shelter, holding on to their cases probably with 

 the hooked lobes at the end of the body. 



Their food consists of vegetable matter or of particles of 

 organic substance in the soil which they swallow, and which 

 often makes the whole intestine appear dark through the trans- 

 parent skin (Fig. 270). On the head are two short antennae, 

 and, round the mouth, mandibles and rudimentary maxillae. 



On the segment just behind the head is a pair of small 

 lobed processes set with minute hooks which aid the larva 

 in moving along its mud burrow. 



Respiration is of special importance to a larva living below 

 the surface in dirty and stagnant water, as the Harlequin 

 larva does. The gnat larva in the same tub or pool must 

 come to the surface frequently to breathe, but the "blood- 



