The Ignorance of Instinct 185 



once more proceeds to close up the cell with the 

 same care as though nothing out of the way 

 had happened. Can she be proposing to use 

 this burrow later, to return to it with a fresh 

 victim and lay a new egg there ? If so, her 

 work of closing would be intended to prevent 

 the access of intruders to the dwelling during 

 her absence ; it would be a measure of prudence 

 against the attempts of other diggers who might 

 covet the ready-made chamber ; it might also 

 be a wise precaution against internal dilapida- 

 tions. And, as a matter of fact, some Hunting 

 Wasps do take care to protect the entrance to 

 the burrow by closing it temporarily, when the 

 work has to be suspended for a time. Thus I 

 have seen certain Ammophilae, whose burrow is 

 a perpendicular shaft, block the entrance to 

 the home with a small fiat stone when the 

 insect goes off hunting or ceases its mining 

 operations at sunset, the hour for striking work. 

 But this is a slight affair, a mere slab laid over 

 the mouth of the shaft. When the insect 

 comes, it only takes a moment to remove the 

 little flat stone ; and the entrance is free. 



On the other hand, the obstruction which 

 we have just seen built by the Sphex is a solid 

 barrier, a stout piece of masonry, where dust 

 and gravel form alternate layers all the way 

 down the passage. It is a definite performance 



