662 
THE STUDY OF INSECTS. 
by a number of species. In California there is a single repre¬ 
sentative of a third genus, Polybia (Po-lyb'i-a). This genus 
differs from the other two genera, in having the first abdom¬ 
inal segment long and slender, forming a peduncle. Our 
species is Polybia jlavitarsis (P. flav-i-tar'sis). 
Polistes .—In this genus the abdomen is long and spindle- 
shaped (Fig. 789). The species 
are black, ringed with yellow, or 
are brownish. Their nests con¬ 
sist each of a single comb, sus¬ 
pended by a peduncle, and are 
\ h not enclosed in an envelope (Fig. 
790). In the fall these fellows 
are quite as familiar as the mud- 
Fig. 789.— Polistes. daubers, which they resemble in 
color. However, they are easily distinguished from these, 
as the abdomen is not on such an absurdly long peduncle, 
Fig. 790.—Nest of Polistes. 
and their wings fold like fans. They come into our houses 
searching for warm crevices in which to pass the winter. 
Vespa .—To this genus belong the wasps commonly 
known as yellow - jackets and as hornets. With these 
insects the body is comparatively short and 
rather stout (Fig. 791); the abdomen is at¬ 
tached to the thorax by a very short peduncle ; 
the color is black, spotted and banded with 
yellow or yellowish white. The species of this 
genus enclose the combs of their nest with a 
spherical paper envelope (Fig. 792). Any person fig. 791.— Ves/a. 
