142 



WASPS 



[CH. V 



asp , 

 Afte 



skins periodically. The cells are made longer by the 



queen as the increasing size of 



the grubs demands. The grubs 



are placed head downwards in 



their cells so that their mouth 



is at the open end. They at 



first retain their position and 



avoid falling out by means of 



the cement by which the egg 



is glued to the cell wall, for 



the hinder segments remain in Fig> 2? 



a portion of the egg-shell. 



Subsequently the curved shape ap 



of the body causes it to abut 



firmly on both dorsa. and 



ventral sides against the walls 



of the cell. 



When full grown the grub spins a cocoon within the 

 cell, lining the entire cavity sparsely, but closing the bottom 

 with a tough silken floor which projects as a dome beyond 

 the lower end. In this operation the grub completely 

 reverses its position, turns, in fact, head over heels in order 

 to apply silk discharged at the anterior end of the body to 

 all parts of the cell wall. Hitherto no faeces have been 

 extruded: now, however, a black mass, composed of a sac 

 containing the entire faecal accumulations of larval life, is 

 ejected. This mass remains attached to the top of the cell 

 and becomes flattened by the pressure of the larva against 

 it. A marked change now takes place in the form of the 

 animal. A moult occurs shortly after the completion of 



Diagram of \vr 

 nest at an early stage. (After 

 Janet.) 



Entrance to nest. c. Comb. 

 1, 2. 1st and 2nd coverings 

 now largely removed to make 

 room for growing comb. 3, 4, 

 5. Corresponding coverings 

 still complete. 6. 6th cover- 

 ing as yet not finished. 



