132 SOME NOTES ON THE LIFE HISTORY 



behind the legs, and this state lasts approximately 48 hours, 

 after which the pupa emerges from the last larval skin but does 

 not separate from it, the skin being retained at the extremity 

 of the abdomen, as the connection between the pupa and 

 the leaf, on which it remains stationary. 



Pupa. 



The pupa stage (Fig. 3) lasts from 4 to 5 days, as a rule, 

 though some few exceptions remain as long as 7 days and yet 

 eventually turn into the fully developed imago. 



During the pupa stage no external changes take place, 

 except that on the ventral surface the limbs of the insect may 

 be observed developing. 



Imago. 



The imago when it is ready to burst forth from the pupa, 

 begins to stretch and strain until it breaks the pupa skin near 

 its head. It then pushes out its head and chitinous head 

 shield until it can release its antennae and front pair of legs. 



The elytia may then be observed to be quite soft, folded 

 closely around the thorax and abdomen, and as it emerges from 

 the pupa skin the elytra gradually spread out, while at the 

 same time the insect pulls out its second and third pairs of 

 legs. 



Until the actual process of emergence has been closely 

 watched, it is hard to realize how so large an insect can have 

 come out of so small a pupa case. 



The imago is at first of a clear yellow colour without a 

 spot visible on it. The black spots appear in about an hour, 

 but if the insect be observed under a microscope the positions 

 of the spots which are to come are found to be marked by 

 pores in the elytra which have a speck of black pigment visi- 

 ble. There are some 15 or 16 of these pores to each black 

 spot. 



About half an hour after emerging from the pupa the in- 

 sect unfolds its wings so that the ends emerge beyond the 

 elytra, but it does not, at this stage, attempt to fly, or even to 



Jour. Straits Branch 



