148 SOCIAL LIFE IN THE INSECT WORLD 



The larva is a mags^ot curved like a hook, carrying 

 on its back an ample pouch or hunch, forming part 

 of its alimentary canal. The reserve of excreta in this 

 hunch enables it to seal accidental perforations of the 

 shell of its lodging with an instantaneous jet of mortar. 

 These sudden emissions, like little worm-casts, are also 

 practised by the Scarabajus, but the latter rarely makes 

 use of them. 



The larvae of the various dung-beetles utilise their 

 alimentary residues in rough-casting their houses, which 

 by their difnensions lend themselves to this method 

 of disposal, while evading the necessity of opening 

 temporary windows by which the ordure can be ex- 

 pelled. Whether for lack of sufficient room, or for 

 other reasons which escape me, the larva of the 

 Sisyphus, having employed a certain amount in the 

 smoothing of the interior, ejects the rest of its digestive 

 products from its dwelling. 



Let us examine one of these " pears " when the inmate 

 is already partly grown. Sooner or later we shall see 

 a spot of moisture appear at some point on the surface ; 

 the wall softens, becomes thinner, and then, through the 

 softened shell, a jet of dark green excreta rises and falls 

 back upon itself in cockscrew convolutions. One 

 excrescence the more has been formed ; as it dries it 

 becomes black. 



What has occurred ? The larva has opened a 

 temporary breach in the wall of its shell ; and through 

 this orifice, in which a slight thickness of the outer glaze 

 still remains, it has expelled the excess of mortar which 

 it could not employ within. This practice of forming 

 oubliettes in the shell of its prison does not endanger the 



