THE INSECT WORLD. 



407 



times become of enormous size, many hundreds of individuals 

 being found in a single nest in the latter part of the season. 

 Durability is not looked for by the insects, and the winter storms 

 and snows disintegrate the paper structures, so that in spring it 

 is rarely possible to find them, however abundant they may have 

 been during the summer previous. 



Wasps are beneficial, as a whole, since they feed largely upon 

 other insects and never directly upon crops. They are a nui- 



FiG. 463. 



Nest of Polistfs gallicola. 



sance sometimes in the orchard, where they are apt to attack all 

 fruits that show the least trace of injury or decay, and they have 

 been accused, as, indeed, have the bees as well, of actually punct- 

 uring juicy specimens to get at the liquid contained in them. 

 Some of the species are undoubtedly useful in poUenizing fruit 

 flowers, but there are none of pre-eminent advantage in this di- 

 rection. 



The last family in the order contains the bees, and these, as in 

 the wasps, may be either social or solitary. The solitary bees 

 are those in which male and female only are developed, and their 

 habits in nest-building resemble in many cases those of the 

 wasps. Thus, we have species that build in the ground, those 

 that make cells in the pith of plants, others that are true carpen- 

 ters and bore tunnels in solid wood, and, in short, we may find 

 bee homes in much the same situation that we find wasp domi- 

 ciles. Their cells may be distinguished, however, in all cases by 



