FOREST SHELL-WASP 413 



sewage showing through its transparent skin. In the ease of 

 the shell- wasp, it changes from a clouded honey color to white 

 slightly tinged with yellow. It also becomes more opaque. 



Ten days after excretion the insect pupates. Then 

 comes another wait of three weeks before the final wasp is- 

 sues from its cell. 



During these twenty-one days, the pupa receives its fin- 

 ishing touches — at first, when the transformation from the 

 larval state takes place, there is no dark pigment in the body. 

 It is yellowish white and rather translucent. Color appears 

 first in the eyes which turn light lavender, then brown and 

 finally black. Next, the pigment appears in the remainder 

 of the head. Then, as though coming through some hidden 

 tunnel below the flesh, it appears as a mere dot of dark fluid 

 in the center of the thorax. Slowly the dot expands, throw- 

 ing out arms of color which later combine and fill the entire 

 thorax with pigment, like a rocket that unfolds its display 

 in the sky. Next the slender petiole of the abdomen becomes 

 clouded. This soon gives place to darker color while its re- 

 cent cloudiness appears in the abdomen itself. At length 

 the entire insect turns black save for the three small orange- 

 yellow patches on its abdomen. 



This general dullness is due to the pupal skin in which 

 the finished wasp is now resting. We see it through this 

 delicate membranous covering which is immeasurably thin 

 and fits the insect as closely as her own external skeleton. 

 Under the transparent covering the insect appears dull, but 

 otherwise quite normal except for her wings. Her legs and 

 antennae are of proper length, her head and body neatly 

 proportioned, yet her wings are but a third the natural size. 

 They are hollow appendages intricately folded and held in 

 place by the wing bags of the membranous covering. Later 

 with the pupal skin of which they are a part, these bags are 

 shed, releasing the true wings which unfold to their full ex- 

 tent under a pressure of liquid Avhich flows into them from 



