HYMENOPTERA OR BEES, ANTS, WASPS, ETC. 65 



den to her inconspicuous little hole, and after dragging 

 her prey in she lays an egg upon it and covers it over 

 with earth. Often several caterpillars are put into the 

 same hole and after the last one is disposed of, the wasp 

 fills up the hole and leaves it. The mud daubers fre- 

 quently build their nests on the sides of buildings; they 

 make cells of mud and commonly store them with para- 

 lyzed spiders. 



In the social wasps we have a worker caste consisting 

 of sterile females which show few external differences, ex- 

 cept in size, from the fertile females. The best known 

 species are the yellow jackets and hornets. Both these 

 forms build rather large nests of a paper-like substance 

 which they make by chewing up wood. Out of this paper 

 they construct remarkably neat and regular six-sided cells 

 which are placed with their open ends hanging downward. 

 There are commonly several tiers or stories of these cells 

 one over the other, and the whole is surrounded with a 

 paper envelope with a hole in the bottom. The large 

 white-faced hornets attach the nest to the branch of a 

 tree, and it is not safe to molest them as the hornets 

 have a very irritable temper and can sting with consider- 

 able severity. The nests of some species of yellow jackets 

 'are commonly found under the ground while others may 

 be attached to buildings or trees. These creatures are 

 likewise very pugnacious, but not so formidable as the 

 hornets. 



ANTS 



One would not at first sight regard the ants as members 

 of the order Hymenoptera because most of them are 

 wingless, but study of their structure shows them to be 

 related to the bees and wasps. It is only the workers, 

 and these are by far the most numerous, that never de- 



