HORNETS AND YELLOW-JACKETS. 



destructive Lepidopterous and Coleopterous larvag, of 

 which they must destroy many thousands every year. 

 As with most solitary wasps, the prey is first paralyzed by 

 stinging and then packed in the nest as food for the larva 

 which will hatch from the egg laid before the nest is sealed. 

 Certain genera may be separated as follows: 



1. Abdomen petiolate 2. 



Abdomen sessile, or nearly so 3. 



2. Head large, quadrate, much expanded behind the 

 eyes, making the cheeks broad ; clypeus broader than long, 

 concealing the mandibles, when they are closed . . . Zethus. 



Head not. expanded behind the eyes, which almost 

 entirely cover the cheeks; clypeus longer than broad; 

 mandibles, when closed, extending beneath the head 

 like a beak Eumenes. 



3. First abdominal segment funnel-shaped Nortonia. 



Not so 4. 



4. Maxillary palpi with 6 joints Odynerus (Plate XC). 



Maxillary palpi with less than 6 joints 



Monobia (Plate XC). 



VESPID^E 



This is the family which is usually concerned when people 

 speak of Wasps, Hornets, or Yellow-jackets. They are 

 all social creatures (among themselves) that make nests 

 of "paper" formed from chewed wood. In the South there 

 is Polybia, whose abdomen is short and ovate beyond the 

 first, petiolate, segment; several mothers unite in producing 

 the young of a colony. We may, for practical purposes, 

 group our northern species in two genera: Vespa, first 

 abdominal segment very broad and sharply truncate 

 in front; and Polities, this segment long and gradually 

 narrowed in front to a more or less distinct petiole. In 

 these, each colony is a single family in which unmarriageable 

 daughters help to build the house, keep it clean, and feed 

 the younger children. The food consists of chewed-up 

 animal matter, such as caterpillars, but some species use 

 honey and pollen also. The larvae are fed from day to 

 day, or oftener, no food being stored for them. 



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