COCOONS. 177 



America is popularly called the tumble-bug — the latter inappro- 

 priate monosyllable being indiscriminately used for every insect 

 that even looks like a beetle. 



There is also in the British Museum one enormous cocoon 

 made of clay. It is almost the size of a six-pounder cannon-ball, 

 with walls of such thickness that the hollow in its centre is bare- 

 ly the size of a crab-apple. The weight of this cocoon is enor- 

 mous, when the size of its inmate is considered, and that so com- 

 paratively small a beetle should construct and roll so large a ball 

 seems almost incredible. The beetle belongs to the genus Copris. 

 There is the cocoon of another species of Copris, but in this case 

 the walls are very thin, and the entire ball would go into the hol- 

 low of that which has just been described. A British beetle, 

 Qeotrupes vernalis, also makes a cocoon about the size of that 

 which has just been mentioned. It is made of mixed clay and 

 cow-dung, and specimens may be seen in the Museum. 



Cocoons of Scarabasus and Goliath. 



Perhaps the most extraordinary of these cocoons is that which 

 is represented in the illustration. This is made by one of the 

 gigantic beetles of the tropics. The insect which made it has no 

 English name, but is scientifically called Goliathus Drurii. This 

 wonderful cocoon is as large as a swan's egg, and, as may be seen 

 by reference to the illustration, has very thin walls in proportion 

 to its size. It is strengthened by a remarkable belt, which runs 

 around its centre, exactly like that of the bullet which is used for 

 the two-grooved rifle. How the belt is formed is perfectly un- 

 known, as is its use, unless the strengthening of the walls be its 

 only object. I have carefully examined the cocoon itself, and 



M 



