86 FIRST BOOK OF ZOOLOGY. 



tered to .the wall, rough and irregular in appearance, and at 

 first sight might be mistaken for the work of some mis- 

 chievous boy. 



FIG. 84. A MUD-WASP'S NEST, HAVING Two CELLS. 



Fig. 84 represents their general appearance, for, rough 

 as the} 7 appear, on close examination they are seen to be 

 constructed very systematically the soft clay of which 

 they are built being laid on in alternate layers, looking 

 something like a braid ; while the upper portion, being built 

 of looser and coarser material, is put on in irregular lumps. 

 With a thiii-bladed knife these mud-cells may be scraped off, 

 and sometimes can be pulled away with the fingers. Upon 

 opening them they will be found either filled with little 

 spiders, or containing yellow-colored larvse, pupee in brown 

 skins, or wasps. Their history is as follows : 



82. When the mother-wasp gets ready to lay her eggs, 

 she first builds these curious nests of mud, which she collects 

 from the streets, or by the sides of brooks in clayey soil. Hav- 

 ing finished one cell, she deposits therein an egg, and then 

 collects a number of small spiders with which she completely 

 fills the cell. After this is done she closes up the top of the 



