hornets attack at once when their nests are disturbed and ave 
capable of inflicting extremely painful stings. 
Vespula arenaria arenaria (Fab.) is probably the most common 
species of yellow jacket in eastern United State It also occurs 
throughout the remainder of the United States, and in Canada, 
and Alaska north to the Arctic Circle. Adults a: 2 black and yel- 
low with black predominating. The legs are yellow with the 
femora mostly black, and the length is about 12 mm. Nests (fig. 
203) are usually built in the ground, with an exit hole leading to 
the outside. This species also inflicts severe stings and it often 
attacks in force when its ne is endangered. It is a common 
species around picnic tables where it is often a nuisance. 
The genus Polistes Latreille contains the familiar wasps whose 
nests are so frequently encountered hanging under the eaves of 
buildings and in various and sundry other places. They differ in 
appearance from the hornets and yellow jackets in having long 
and spindle-shaped abdomens. The nest consists of a single comb 
suspended by a peduncle, and it is not enclosed in an envelope. It 
is usually rather small, although some may be several inches in 
diameter. The adults of a number of species collect lepidopterous 
larvae as food for their young and, where abundant, are appar- 
ently capable of exercising a considerable degree of control of 
their hosts. Like hornets and yellow jackets, these insects are 
vicious stingers, and their nests should be approached with 
caution. 
FAMILY POMPILIDAE 
Members of this family are predacious or parasitic on various 
species of spiders. The adults are often seen visiting flowers and 
are noted for their extreme activity and ability to run. Their 
nests are usually found in the ground, but some consisting of mud 
cells are constructed under logs or stones and in other protected 
places such as holes in wood. 
SUPERFAMILY SPHECOIDEA 
All members of this superfamily are predacious on other in- 
sects. The majority of species nest in burrows in the soil; the 
remainder build nests of clay, mud, or sand, or in the stems of 
plants or various kinds of cavities in which they store paralyzed 
prey which serves as food for their progeny. Host preferences are 
varied, including spiders and most of the more common orders of 
insects. Adults generally can be recognized by the structure of the 
pronotum which does not extend back to the tegulae, by their un- 
jointed trochanters, by the absence of dilation in the hind tarsus, 
and by the simple pubescence of the head and thorax. 
FAMILY AMPULICIDAE 
This family is represented in North America by only two gen- 
era and three species. As far as known, they nest in twigs, under 
bark, and under litter on the ground. Their prey consists of im- 
mature cockroaches. 
