250 ELEMENTARY ZOOLOGY. 



service. They carry the pollen from flower to flower in 

 their search for nectar, and thus bring about the cross- 

 fertilization which is apparently so valuable to plants 

 (Fig. 28) . It is in the caterpillar stage that they are most 

 injurious to human interests. The caterpillars, often 

 known as "worms," are voracious feeders and eat leaves 

 of all sorts, fruits, seeds, and the like (Figs. 93-95). One 

 form, the larva of the clothes moth, lives on animal 

 matter, such as furs, woolens, and hair. The silkworm, 

 which lives largely on the mulberry leaves, is the most 

 useful member of the order.. 



264. The Hymenoptera (Ants, Bees, and Wasps). 

 This seems the most highly developed division of the 

 insects; at least they have impressed man, as no other 

 insects have, with their marvelous instincts in care of 

 young, in making homes, in storing food, and in organizing 

 into social communities. They have two pairs of mem- 

 branous wings; they undergo a complete metamorphosis, 

 the larvae being white grubs; and their mouth parts may 

 be formed either for biting or for sucking or for both at 

 once. 



Not all of the members of this group are social. There 

 are stages extending all the way from wholly independent 

 life, as in the solitary wasps and the carpenter bees, up to 

 the complex social life of the honey bees and the ants. 

 This social life and the making of homes centers about the 

 laying of eggs and the rearing of young. It may also 

 imply the laying up of food for winter use, but this is 

 not always true. These homes may be borings in the 

 ground or in wood; they may be manufactured entirely 

 by the animal of mud (dirt-daubers), or of wood pulp 

 spread out in the form of a paper (as the hornets), or of 



