The Hunting Wasps 



a measure of prudence against the attempts of 

 other diggers who might covet the ready- 

 made chamber; it might also be a wise pre- 

 caution against internal dilapidations. And, 

 as a matter of fact, some Hunting Wasps do 

 take care to protect the entrance to the bur- 

 row by closing it temporarily, when the work 

 has to be suspended for a time. Thus I 

 have seen certain Ammophilas, whose burrow 

 is a perpendicular shaft, block the entrance 

 to the home with a small flat 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 perform- 

 ance and not a provisional defence, as is 

 proved by the care with which it is con- 

 structed. Besides, as I think I have shown 

 pretty clearly, it is very doubtful, considering 

 the way in which she acts, whether the Sphex 

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