VIII MAY-FLIES 289 



" These larvae arc rarely, if ever, seen swimming in 

 the water. It is true that they can swim by a kind of 

 serpentine movement, bending the head now down, 

 now up, but they always keep to the banks out of 

 reach of the current. They can very rarely be seen 

 out of the mud, in which they make for themselves 

 long cylindrical and horizontal burrows. 



" As the Bees in their own wonderful way make 

 homes out of wax, so the larvae of the Ephemera 

 excavate out of mud the tubes in which they dwell. If 

 they are taken out of their tubes, they can only creep 

 readily when the bottom is so flat as to support the 

 whole length of the body. Although they are ordin- 

 arily immersed in water and can swim, I have found 

 on taking a number of them out of their tubes, that 

 they at once fall on their backs as if paralyzed, and 

 are not able to right themselves. But within their 

 burrows they can move quickly backwards and 

 forwards. The same is true of various other larvae 

 which burrow in trees, fruits, leaves or galls. The 

 Cossus when taken from its hole in a tree covers its 

 whole body with a web, and supported by this, it is 

 able to make a new hole in the wood, but if left with- 

 out support, or some fixed object against which the 

 body can be pressed, it is quite unable to bore. The 

 larva of the Ephemera is so helpless outside its tube, 

 that if while swimming in the water it ceases to exert 

 itself, it falls at once to the bottom, and there lies upon 

 its back. 



" As soon as the larvae escape from the egg, they set 

 about making their burrows, and these are gradually 

 increased in size as the larva grows. The All-wise 



U 



