262 



INSECT LIFE. 



If the reader will go to the nearest clump of sumachs 

 and break off a dozen dead branches, and then split 

 them carefully, he is almost certain to 

 find one or more such nests. Fig. 237 

 represents a common type of nest found 

 in sumach. 



These nests are made by solitary in- 

 sects — that is, a single female working 

 alone builds a nest in which to lay her 

 eggs. Representatives of several fam- 

 ilies utilize dead branches of pithy plants 

 for this purpose. In such places can be 

 found nests of solitary bees, of solitary 

 wasps, and of digger-wasps. 



The parent insect finds an entrance 

 through a knothole at the side or at 

 the end of the branch when the tip has 

 been broken off. She excavates the pith 

 for a considerable distance ; then she 

 collects a quantity of food and places it 

 in the lower part of this tunnel, after 

 which she lays an egg upon it, and 

 builds a partition across the tunnel just 

 above the egg and the supply of food. 

 She repeats this process until the tunnel 

 is divided into several cells, each con- 

 taining an egg and a quantity of food. 



When the larvae hatch from these 

 ^^est ^S&^ each finds in its cell sufficient food 



When 



111 



Fig. 237.- 

 of Trypoxyion to nourish it till it is full-grown. 



JrigiduTTi, , 111! 



this Stage is reached the larvas of some 

 species spin cocoons about their bodies, within which 

 the pupa state is passed ; in other species the larvas 



