BEES, WA^S, ANTS, ETC. 



533 



The sub-family Eumeninffi is most readily separated from the VespinaB by the 

 tarsal characters. In this group the claws are armed with a tooth, while in the Ves- 

 pinsB they are simple. With the solitary wasps there are but two forms, male and 

 female, each female performing the dual duties of queen and worker, building and 

 provisioning her nest alone. The members of this sub-family exhibit considerable 

 diversity in the manner in which they build their nests. Some make them of mud in 

 the chinks of walls or other convenient holes. Some fasten their mud nests to the 

 inner surface of walls or roofs of outbuildings, while others fasten similar nests to 

 shrubs growing in the open air. Many species excavate tunnels in wood, availing 

 themselves of the easily excavated pith of certain plants, while others bore into solid 

 wood. Certain species again tunnel into the ground and into sandy banks. The 

 nests are provisioned in a manner similar to that employed by the digger wasps. 



The most important genus in this group is Odynerus. With the insects of this 

 genus the abdomen is sessile or subsessile, and the shape of the body, and oftentimes 

 the coloration, resemble those of the social wasps commonly known as " hornets " or 

 " yellow-jackets." While some of the species of Odynerus are true wood and sand 

 burrowers, others again will construct their cells in any convenient cavity. The cells 

 of 0. albophaleratus have been found in the deserted gall of Diplolepis confluens, 

 arranged around one side of the gall, with 

 their holes pointing towards the centre, 0. 

 quadratus has been known to make use of 

 hollow reeds, of the accidental folds in a 

 sheet of paper, and even of the barrels of 

 a double-barrelled pistol which hung against 

 the posts of a garden arbour. A specimen 

 of Odynerus flavipes is said to have made 

 its cell in the hole of an old cotton-spool. 

 These insects store up a variety of species, 

 seeming to prefer small lepidopterous larvae. 

 Several species of the Ichneumonid genus Cryptus have been bred from Odynerus cells 

 in Europe, and Cryptus junceus has been bred from the cells of Odynerus birenimacu- 

 latus in New Jersey. 



The typical genus Eumenes may be recognized by the very long pedicel of the 

 abdomen. This is formed by the first abdominal segment, and is either linear or sub- 

 campanulate, and about as long as the thorax. The remainder of the abdomen is 

 pyriform. The most common North American species is Eumenes fraterna. This 

 species makes globular mud cells, very regular in form, and each furnished with a 

 short neck, and attaches them to plants. In the eastern states the larv£e of the 

 spring canker-worm (Anisopteryx vernata) is frequently found stored up in the cells 

 of this species. The larva of the wasp occupies about a month in its development, 

 and the adult insect issues through a hole which it breaks in the side of the cell. 



With the Vespinse or social wasps, there are, as with other social Hymenoptera, 

 three formS,' 'males, females or queens, and workers. The habits of these insects rival 

 in interest those of the hive-bee, of which so much has been written. It is, however, 

 much more difficxilt to study these insects than either the hive-bee or ants. As most 

 of the species are very irritable, and possessed of quite venomous stings, it requires 

 considerable tact and courage to investigate their habits closely. 



The size of the communities of social wasps varies, at the season when they are 



Odynerus fiavipes and cell in a spool. 



