28 Insect Architecture. 



species being of a green colour, and without feet. She 

 fixes the caterpillars together in a spiral column : they cannot 

 alter their position, although they remain alive. They are 

 an easy prey to their smaller enemy ; and when the grub has 

 eaten them all up, it spins a case, and is transformed into a 

 pupa, which afterwards becomes a wasp. The number of 

 caterpillars which is thus found in the lower cavity of the 

 mason-wasp's nest is ordinarily from ten to twelve. The 

 mother is careful to lay in the exact quantity of provision 

 which is necessary to the growth of the grub before he quits 

 his retreat. He works through his store till his increase in 

 this state is perfected, and he is on the point of undergoing 

 a change into another state, in which he requires no food. 

 The careful purveyor, cruel indeed in her choice of a supply, 

 but not the less directed by an unerring instinct, selects 

 such caterpillars as she is conscious have completed their 

 growth, and will remain thus imprisoned without increase or 

 corruption till their destroyer has gradually satisfied the 

 necessities of his being. " All that the worm of the wasp," 

 says Keaumur, " has to do in his nest, from his birth to his 

 transformation, is to eat." There is another species of wasp 

 which does not at once enclose in its nest all the sustenance 

 which its larva will require before transformation, but which 

 from time to time imprisons a living caterpillar, and when 

 that is consumed, opens the nest and introduces another. 



[The upper figure in the accompanying illustration ex- 

 hibits two of the curious towers built by this interesting 

 insect and drawn of their natural size. 



The insect is one of the most plentiful in England, and 

 can be found on sunny days, flitting about sand -banks and 

 making its curious habitations. The length is nearly half an 

 inch, and the colour is black, variegated with five yellow 

 bands upon the abdomen. 



The lower figure represents the habitations of one of the 

 British solitary wasps, Pompilus punctum, and is given in 

 order to show a curious resemblance in the structure. The 

 specimen from which the sketch was taken was found under 

 the eaves of a roof which protected a bee-hive. The cells 



