ENTOMOLOGY IN OUTLINE HYMENOPTERA. 119 



their eggs and provide for their young. These nests are usually pro- 

 vided with food for the young wasps in the form of the preserved bodies 

 of other insects or spiders. Many species provision their nests with 

 caterpillars, others with spiders. The parent wasp possesses some 

 kind of fluid which she injects into the victim, and which renders it 

 apparently senseless, but which, instead of killing, preserves its life, 

 and it will remain in this condition perfectly fresh until required by 

 the larva? of the wasps for food. 



Comstock gives us fourteen families under the superfamily Sphecina, 

 to most of which only a passing allusion' is necessary. 



The family Mutillidse are the velvet-ants. The females are wingless 

 and strongly resemble ants in appearance, but their bodies are covered 

 with a dense growth of hair, which has given them their common name. 



The family Seoliidse very strongly resembles the foregoing family. 

 Members of this family do not build a burrow, but find the larvaB of 

 other insects in the ground, and upon these they lay their eggs, which, 

 hatching, consume the host insect. So far, this wasp may be regarded 

 as beneficial. 



The family Sapygidse is a small one, the members of which are 

 usually found in the nests of bees. It has no economic importance. 



The family Pompilidse includes about a hundred and twenty species, 

 and they are commonly known as the spider-wasps, on account of their 

 habit of provisioning their nests with spiders, which they sting and 

 reduce to a dormant condition. They are generally slender insects 

 with long legs, and usually brilliantly colored and beautifully marked. 

 While generally of moderate size, some of the species are very large, 

 and here we find the well-known tarantula-hawk (Pepsis formosa-). 



The family Spheeidse comprises the thin-waisted wasps, and includes 

 the well-known mud-daubers. These are commonly known as the 

 thread-waisted wasp, on account of the thin, thread-like process which 

 connects the abdomen with the thorax, and which is composed of the 

 first two segments of the abdomen. This family is a very conspicuous 

 one and embraces about seventy species in the United States, most of 

 them well known from their peculiar form and habits. They build 

 their cells from mud, and stock them with spiders or caterpillars, after 

 first depositing an egg in the bottom. When hatched, the young larva 

 finds an abundance of preserved food awaiting it, and remains in the 

 cell until it has passed through all the changes, when it emerges a 

 perfect insect. 



