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INTRODUCTION TO ZOOLOGY 



CHAP. 



This yellowish-brown fly is rather sluggish in its habits, sitting 

 for long together on a stone by the water, with its long 

 wings folded flat over its body so that only one pair can be 

 seen. It flies slowly and heavily, and can easily be caught 

 in the hand. 



Each Stone-fly has a long pair of antennae projecting in 

 front, and also a pair of delicate jointed appendages at the 

 end of its tail. 



The thorax is peculiar, for the three segments which form 

 it are unusually large and clearly marked, forming with the 

 head about half the length of the body ; in consequence the 

 bases of the two pairs of wings are rather widely separated. 



/I. 



FIG. 233. Chloroperla virescens. 

 A, Dorsal view ; B, ventral view ; e, egg mass being discharged ; C, one egg enlarged. 



The insects mate on the ground, and the small black eggs, 

 held together by a delicate membranous capsule, are carried 

 for some time adhering to the abdomen of the female, and 

 are then dropped in the water. Similar eggs are shown in 

 Fig. 233, which represents the closely allied genus, Chloroperla, 

 a yellow and much smaller fly. 



The Stone -fly larvae, sometimes known as 

 Creepers, which hatch from the eggs, can swim freely 

 in the water by the movements of the body, but they usually 

 hide under stones. This larva, like the imago, bears two long 

 antennae on its head, and two antenna-like appendages at the 

 end of its body. It breathes by means of small tufts of thread- 

 like tracheal gills, of which there are two pairs on each thoracic 



The Larva. 



