THE HYMENOPTERA 355 



which is stored there. After constructing the nest, either by digging, 

 building, or otherwise, the parent starts out to provision it. The food 

 differs with different species. Some take certain species of grasshoppers, 

 others, flies: Homoptera, Hemiptera, Hymenoptera, Lepidoptera larvae, 

 some Coleoptera, and Spiders, are also listed as the prey of digger wasps 

 of various species. 



When one of the wasps finds an insect of the desired kind she attacks 

 and stings it, generally not killing, but only partly paralyzing it and ap- 

 parently chiefly the locomotor centers, so that it cannot escape. The 

 prey is then grasped by the wasp and carried to the nest. In some cases 

 flight is possible to the wasp carrying this load, but in many cases the 

 prey is far too heavy for transfer in this way, at least in the case of those 

 wasps which burrow in the earth, and it is therefore dragged along the 

 ground to the nest. How the wasp knows the direction to take and 

 how finally to locate the hole it is practically impossible to determine, 

 but in most cases the insect seems to have little difficulty. 



Once arrived at the nest the prey is dragged into it and if it alone 

 provides a sufficient food supply for the young wasp to be developed 

 there, the parent now lays an egg on it and then closes up the opening 

 of the nest. In the case of nests in the ground this is accomplished by 

 scratching in dirt from around the hole and packing it in firmly. In 

 three or four cases, species of the wasp genus Sphex have been seen by 

 different observers to pick up a tiny pebble with their mandibles and, 

 using it like a hammer, pound down more firmly the earth filled into the 

 hole. This may perhaps be interpreted as representing the "Stone 

 Age" in the development of insects! 



If the single insect captured will not provide enough food for the 

 young wasp, the parent proceeds to bring in more, until sufficient has 

 been supplied, after which the opening is closed and another nest or 

 cell, according to the kind of wasp concerned, is begun. In a few species 

 the prey, instead of being paralyzed, appears to be killed and it is claimed 

 that the wasp brings fresh supplies of food from day to day for the food 

 of its young. 



Detailed studies on the lives and habits of these wasps have been 

 recorded by many observers, and the remarkable traits these insects 

 possess form one of the most interesting topics in Entomology. 



One species (Fig. 372) deserves particular attention because of its 

 singular ways. It is a large wasp often called the Cicada-killer (Sphecius 

 speciosus Drury) its body being over an inch long, its abdomen black with 

 yellow marks. It is found over a large portion of the United States and 

 appears during the dog-days in summer. It makes its nests in the ground 

 and provisions them with adult dog-day cicadas (Homoptera), larger 

 and heavier than itself, which it catches in the trees. The prey cannot 

 be carried to the nest by flight but the wasp starts from the point of 



