IMPRISONED CATERPILLARS. 17 



the surface. These are towers built by the sand- 

 wasp of the pieces of rubbish which she scoops 

 out of her mine. She cements them together, and, 

 instead of throwing them away, she lays the masses 

 in regular order until they have assumed the ap- 

 pearance here shown. It has been supposed she 

 does this with a view to keep out enemies and to 

 keep her progeny cool ; just as in a tall house the 

 cellar is its coolest apartment, so the height of the 

 tower in question seems to be an additional protec- 

 tion against the rays of the scorching sun. After 

 it has deposited its egg at the bottom of the exca- 

 vation, the sand-wasp sets out on a foraging 

 expedition, and hunts about until she finds certain 

 green caterpillars. Seizing upon one of these she 

 flies with it to her mine, and then returns for 

 more prey. After collecting about a dozen of 

 these helpless beings, fixing them so that they 

 are hopeless captives inside her dark prison, she 

 bids farewell to the egg, for the future well-being 

 of which she has thus assiduously provided. She 

 takes down her tower of stones, and, with the 

 materials w r hich composed it, fills up the entrance 

 to the cell, thus shutting in both the prisoners 

 and their future devourer in a common dungeoa, 

 c 



