HYMENOPTERA 181 



are governed by reflex action, instincts, or intelligence (in a 

 limited decree, of course), or, what is more probable, by a cer- 

 tain combination of these, they certainly perform many won- 

 derful feats, considering the fact that they have but a single 

 set of tools, the mandibles. They use these to dig and tunnel, 

 to obtain food, and to carry and manipulate their food, to fight, 

 to carry tenderly their eggs and young, or to cut leaves and husks 

 and seeds. Though they have no voice, they are known to 

 communicate by means of touch through the agency of the 

 antennse. It is believed that they recognize friend or foe by 

 the odor. 



The digger wasps (Sphcci'na) are a group of closely allied families of 

 Hymenoptera. They may be distinguished from true wasps by the fact 

 that their wings lie flat above the body, and from bees by the adaptation of 

 their legs for digging and walking. They are all solitary. Each female 

 makes her own nest by burrowing in the ground or in wood, or by construct- 

 ing a tube of mud, or using one found already made. In this nest she places 

 certain insects which she has paralyzed but not killed, by stinging, lays an 

 egg, and seals up the cavity. When the larva hatches it feeds upon the food 

 thus provided for it by the mother. The parasitic forms lay the eggs upon 

 the paralyzed bodies of their hosts, and the guest-species lay them in the 

 nests of other wasps or bees, where the larvae feed upon the food prepared by 

 the host for its young. 



Familiar examples of the digger wasps are the mud daubers (Pelopce'us) 

 of our attics and eaves. It is thought that these wasps find their nests again, 

 after going in search of insects with which to "provision" their nests, by the 

 memory and recognition of localities, for they go from place to place, back 

 and forth in many curious zigzag or circular routes, but find their way back 

 to their nests readily. 



The "tarantula-killer" {Pcp'sis formo'sa), of the West and Southwest, is 

 a large solitary wasp which provisions its nest with the choicest of food, such 

 as tarantulas, though many a hard battle is necessary to procure them. 

 Sometimes the tarantula makes a meal of the wasp instead of becoming food 

 for its young. 



The true wasps (Vespi'na) are characterized by the folding of their wings 

 lengthwise like a fan when at rest, by the kidney-shaped eyes, and by the 

 absence of bristles or spines from the legs. 



One family (Eumcn'idoe) of the true wasps leads a solitary life. One of 

 these {Mono'bia quad'ridens) tunnels into wood and partitions off the 

 tunnel, making a cell for each larva. 



Another species (Eu'hk tx s frah r'nus) is a thorough mason, making little 

 jug- or vase-shaped nests of r\ny or mud which it attaches to the stem of a 

 plant. It provisions it with cateriiillars, often with canker-worms. 



The social wasps (I'ex'pida:) li^•e in communities in spring, summer, and 

 autumn. The males and workers die in the autumn, and the females 

 (queens) hibernate through the winter under logs or stones or in crevices. 

 In the spring each queen starts a colony. She makes a small nest containing 

 a few brood-cells, in each of which she lays an egg. The hatching larvae 



