CHAPTER III 



THE FLY OF CHIRONOMUS 



Order of The larva of Cliironomus, as of other metamorpliic 

 tion. insects, is succeeded by a pupa, and this by a winged 



imago. It would therefore be natural to describe the 

 pupa immediately after the larva. "We do not, however, 

 propose to follow that course here. The pupa of Chiro- 

 nomus is hardly more than the fly enclosed in a temporary 

 skin, and the details of its structure cannot be understood 

 without constant reference to the structure of the fly. 

 It is necessary to know at least the general structure 

 of the fly, in order to follow the changes which take 

 place during the last larval stage. 



The general appearance and habits of the fly have 

 been shortly described on p. 9. See Plate. 

 Head. The head is small, and flattened from before backwards 



(fig. 59). The lunate compound eyes occupy the sides, 

 and almost meet above the antennary bulbs. From the 

 lower or anterior part of the head projects a rostrum^ 

 on which the mouth-parts are carried. A narrow neck 

 joins the head to the thorax. 



When we compare the head of the Chironomus-fly 

 with that of a more primitive insect, such as a cockroach, 

 we see that the lateral lobes, which bear the compound 

 eyes and antennae, have in Chironomus greatly encroached 

 upon the median lobe, almost effacing the broad shield 



