190 THE STUDY OF INSECTS. 



these legs were extended at right angles to the body like a 

 pair of oars. The insect was unable to crawl up the vertical 

 side of the aquarium, and after clinging to it for a short time 

 it would lose its hold and sink back to the bottom. After 

 watching it for a time I lifted it from the water by means of 

 a stick. At this time its wings were in the form of pads, 

 which were but little, if any, longer than the wing-pads of 

 the pupa, as shown by the cast pupa-skin found floating on 

 the water. The instant the creature was free from the water 

 its wings expanded to their full size, and immediately it flew 

 away several feet. In my efforts to catch the insect I found 

 that it had perfect use of its wings, although they were so 

 recently expanded. The time required for the insect to 

 expands its wings and take its first flight was scarcely more 

 than one second ; it was certainly less than two. As these 

 insects normally emerge from rapidly-flowing streams which 

 dash over rocks, it is evident that if much time were required 

 for the wings to become fit for use, as is the case with most 

 other insects, the wave succeeding that which swept one from 

 the water would sweep it back again and destroy it. 



