346 



INTRODUCTION TO ZOOLOGY 



CHAP. 



.-b 



The change to the pupal condition is accom- 

 panied by a change in position as well as an 

 alteration in shape. 



The head-end swells up, as in gnats, into a large rounded 

 mass, in which the eyes, anteftnae, 

 legs, and wings of the adult can be 

 distinctly seen. The abdomen remains 

 long and segmented, but terminates 

 now in two pairs of delicate tail flaps 

 (Fig. 267, a), which, as in the gnat 

 pupa, can be used in swimming if the 

 pupa is disturbed. The movement is 

 a quaint one to watch, for it is very 

 sudden and in a vertical direction 

 downwards, giving the pupa the ap- 

 pearance of making a series of rapid 

 curtseys. If undisturbed the pupa floats 

 head uppermost, either at the surface 

 or a little way below. From its head- 

 mass there projects a pair of breathing- 

 tubes which can make communication 

 with the air above the water. 



From this pupa the imago emerges 

 much in the same way as in the 

 gnat. 



FIG. 267.Cortthra 



plumicornis. ( Pupa . ) 



a, Tail appendages for swim- 

 ming ; b, breathing-tubes. 



Family 2 : CHIRONOMIDAE 

 (MIDGES) 



The members of this family 

 are very gnat-like in form, but 

 they have no projecting mouth- 

 tube Or proboscis and no pierc- FIG. 268. The Harlequin- fly (Chiro- 

 ing Or Sucking mouth -parts. ^wws) 9 , in characteristic resting 

 mL i attitude with the front lem raised 



The Winged insect probably and projecting above the head. 



never feeds. Further, when 



at rest these midges raise the front legs, using them as 

 feelers, whilst the true gnats rest usually with their hind legs 

 raised. Here, as in true gnats, the males have bushy 

 antennae whilst in the females they are scanty and thin. 



