298 F'LASH LIGHTS ON NAIURE 



twists within it, the skin does burst, first over the 

 mouth and head, and then over the central joints 

 of the body. Af^ain the insect twists and wriggles 

 inside this half- broken skin, and again he pushes 

 it backward toward his tail, till at last he has 

 sloughed it all off entirely, and it remains a shriv- 

 elled relic — an empty case — in the spot where he 

 has hitherto lived and breathed and had his being. 

 He is now a true pupa, white at first, but gradually 

 growing a delicate pink, and then rosy. 



Just at first, however, the pupa looks almost as 

 formless as the grub it replaces, revealing no limbs 

 or distinct segments. But little by little, feet and 

 legs and eyes and wings begin to be visible through 

 the semi-transparent shell of the chrysalis. He is 

 changing slowly into a winged insect, and you 

 can watch the change through the delicate horny 

 coverings. 



Stranger still, the Hessian fly at this stage is not 

 torpid and quiescent like most ordinary insects. 

 The piipa, as in many of this family, is locomotive. 

 It has legs and feet, and it can wriggle its way up, 

 as you see in No. 7, where the lower object is the 

 empty larval skin, now deserted by its inmate, 

 while the upper one is the pupa, emerging from 

 the sheath, and making its first experiences of the 

 wide, wide world outside its native leaf-bound 

 hollow. It is ready now to come forth from the 

 pupa stage, and to fly forth in the open air in 

 search of a mate with whom to carry on the serious 

 business of replenishing the fields with new gene- 

 rations of similar larvae. 



