MAY-FLIES AND THEIR NEIGHBOURS 215 



examine the May-fly at this stage in its life-cycle, 

 we observe that the insect is of a dingy hue or grey 

 colour, without a spark of the brilliant iridescence 

 of the wings and body of the perfect May-fly 

 as it flashes in the evening sunlight. Secondly, 

 its forelegs seem too short ; and its tail filaments 

 seem blunt and brief, even its wings are cramped 

 and small. But we must wait awhile. Our insect 

 is resting from the great effort of its recent emer- 

 gence. After a time, which varies very much in 

 individual insects, a little trembling sensation 

 seems to take possession of the May-fly, and then 

 a most beautiful and marvellous emergence and 

 transformation may be witnessed. 



The skin at the back of the head splits, and 

 slowly the head and forelegs of the perfect insect 

 appear through the broken integument, and, most 

 remarkable to see, the forelegs have nearly 

 doubled their previous length. After the head 

 and forelegs are through the insect draws itself 

 forward until its wings and the remainder of its 

 body gradually leave their glove-like vesture, and 

 the same remarkable feature strikes the observer 

 in the apparent telescopic expansion of every part 

 as soon as it leaves this " subimago " skin. The 

 wings become glossy and sparkling as they leave 

 the delicate integument, and the latter almost 

 immediately collapses as the wings are withdrawn. 



