450 TROPICAL WILD LIFE IN BRITISH GUIANA 



terns upon the legs and wings, due to more or less dense 

 hair upon these appendages into which the color gradually 

 flows. Upon the back of the head there is a pattern of hairs 

 and another of longer ones upon the thorax, while the abdo- 

 men likewise suddenly appears clouded with pubescence. 

 Further than this no ground color or markings can be seen, 

 owing to the color being much like the shell of the keg itself. 



In another forty-eight hours, fourteen days after pupa- 

 tion, the fly emerges by splitting the head of the pupal keg 

 in two equal parts. This is a simple operation as the shell 

 is not too substantial, but the new-born fly has yet another 

 task before it will be free. It has yet to dig a passage from 

 its tomb to the light of day. It must be done quickly, lest 

 the wings fill and dry too small and their usefulness be lost. 



For this purpose the insect is supplied with a battering- 

 ram, which protrudes between the eyes at birth from the pu- 

 pal case. It is a transparent sack-like appendage which may 

 be expanded or contracted at will by the fly. It contains no 

 apparatus of any kind, but is apparently the forehead of the 

 insect capable of expansion. To watch the operation of this 

 strange appendage is remarkable. First it swells like a toy 

 balloon when air is blown into it, until it protrudes two or 

 more millimeters in front of the insect's head, pushing the 

 sand or earth in front of it as it increases. This is followed 

 by a rapid deflation of the ram which leaves an indentation 

 into which the fly struggles with great effort. Now the first 

 operation is repeated; the second indentation made and again 

 the insect wedges itself into it. Thus, after an hour, if the 

 fly is fortunate, it reaches the surface of the ground, where 

 it rests for a time to recover its strength, before launching 

 into a new and sunlit world once more to search out the 

 vei-million-nut, this time as a nursery for its own offspring. 



