158 INSECT ARCHITECTURE. 



preceding, she forms a large single groove, sufficient 

 for about two dozen eggs. These eggs are all ar- 

 ranged in pairs, forming two straight Unes parallel 

 to the sides of the branch. The eggs, however, though 

 thus deposited in a common groove, are carefully 

 kept each in its place ; for a ridge of the wood is left 

 to prevent those on the right from touching those on 

 the left — and not only so, but between each egg of a 

 row a thin partition of wood is left, forming a shallow 

 cell. 



Nest of eggs of Saw-Jly, in rose tree. 



The edges of this groove, it will be obvious, must 

 be farther apart than those which only contain a 

 single egg, and, in fact, the whole is open to inspec- 

 tion; but the eggs are kept from falling out, both 

 by the frothy glue before mentioned, and by the walls 

 of the cells containing them. They were observed 

 also, by Vallisnieri, to increase in size like the pre- 

 ceding. 



