HYMENOPTEKA 



149 



The social wasps make nests of a substance closely re- 

 sembling paper which is 

 formed from wood pulp as is 

 paper. These nests may be of 

 many forms and may be found 

 in different situations. The 

 most common ones are found 

 about houses. They are 

 roughly circular, consist of a 

 single layer of cells opening 

 downward and are attached 

 to a ceiling, or to some over- 

 hanging structure that will 

 afford a degree of protec- 

 tion, by a single stalk. The 

 wasps that make these nests 

 are brown in color, more than 

 an inch long and of rather slen- : 

 der and very elegant form. 

 They belong to the genus 

 Polistes. Other social wasps 

 make nests composed of sev- 

 eral layers of cells, all enclosed 

 by an outer wall, the whole 

 structure being oval in form 

 and gray in color. Some of 

 these nests, made by the 

 insects best known as yellow- 

 jackets, are found in the 

 woods, attached to limbs of FIG. 110. Types of Hymenop- 



trees. Others, made by hor- tera - Three lower ^^^ 



... Ants (Formicoidea) ; others, 



nets, may be found either on True wasps (Vespaid ea). 



trees or on the ground, or Slightly reduced. 



