34 



ZOOLOGY 



FIG. 33. Vespa, a hornet. 

 Nat. size. Photo, by W. 

 H. C. P. 



which includes the black and spotted hornets and yellow- 

 jackets, that build great masses of paper combs enclosed 



in a nearly spherical gray paper 

 envelope (Fig. 33). These are 

 found attached to trees or parts 

 of buildings. The paper is made 

 of finely masticated wood-fibre 

 cemented by a secretion. Certain 

 yellow- jackets form nests in the 

 ground. The hornets are well 

 known as among the most vindic- 

 tive of our northern insects, and 

 their sting is capable of produc- 

 ing considerable pain. In all Hymenoptera the pain of 

 the sting is due to the introduction of a poison into 

 the body of the victim through the stinging organ. This 

 poison is secreted by a special gland of the insect. 



The digger and mud wasps (Fossoria 1 ) have the most 

 varied habits. One of the most familiar species is Pelo- 

 pceus, 2 which somewhat resembles a true 

 wasp, but may be easily distinguished 

 from it by the long, slender attachment 

 of the abdomen to the thorax and by the 

 fact that the wings when closed lie flat 

 and horizontal (Fig. 34), while in the 

 true wasps they are folded like a fan. FIG. 34. Digger 

 Other species bore into the pith of plants 

 or make burrows in the ground. Many are 

 predaceous, feeding on spiders, cicadas, etc. 



The ants (Formicidse 3 ) constitute a well-known group 

 having features so marked that other insects, excepting 

 1 From fossor, digger. 2 71-77X65, slime. 3 From formica, ant. 



wasp, showing po- 

 sition of wings. 

 Nat. size. Photo, 

 by W. H. C. P. 



