IV] 



DIPLOPTERA 



39 



up in the cell, but her egg was a new and unfamiliar 

 object : probably she had never seen her own before, 

 and it was certainly asking something entirely outside 

 her previous experience to expect her to place an egg- 

 in the cell by means of her jaws and feet. Here then 

 instinct failed; and the failure revealed the utter 

 absence of reason from her other actions in these 

 novel circumstances. 







Fig. 6. Nest of Odynerus 



e = egg of Odynerus suspended by silk thread 

 1 = caterpillars stored by Odynerus 



All these mud-wasps appear to behave in the 

 same way in suspending their egg by a thread to 

 the roof of the cell. The egg is at the far end of 

 the cell, and the caterpillar first brought in lies 

 closest to it : the others lie in order between this 

 and the cell-door. When the grub first hatches 

 from the egg it is very small and weak, and might 

 easily receive a fatal injury from the semi-paralysed 



