109 
PREDACEOUS ENEMIES OF THE LARGER LARV^ AND MOTHS. 
Foremost amon^ the predaceous enemies of the bollworm are several 
species of Polistes. There are three species which frequent the cotton 
fields: P. annidarw Linn., a large black form with black wings and a 
single black cross band of yellow near the base of the abdomen; P. 
ruhiginosus Lepel., a large, slightl}^ stouter, rust-red species, with dark 
wings; and P. texanus Cress., a smaller, more slender, and variably 
striped form with paler wings. Polistes annularis builds large nests, 
often nearly a foot in diameter (see PI. XVIII, fig. 1), and sometimes 
containing upward of a thousand cells; the others construct smaller 
nests, generall}^ from 3 to 6 inches in diameter, and containing a pro- 
portionatel}^ smaller number of cells. 
Fig. 16.—Chrysopa ocidata: adults, eggs, larvse, and cocoon (from Marlatt). 
The adults of Polistes pass the winter hibernating in protected places 
near the cotton fields, and early in the spring each female starts a new 
nest. The larvse of the wasps are fed upon chewed-up bits of caterpillars 
captured by the wasps. By the middle of the summer, when the bollworm 
is attacking cotton, their colonies are well grown and vast numbers 
' of the wasps are circulating through the cotton fields in their tireless 
search for caterpillars. Once a bollworm is discovered, the Polistes 
seizes it just back of the head with her mandibles and in the case of 
a large worm usually stings it to death. Then, after a preliminary 
chewing, she carries it off to the nest, where it is distributed and fed 
to the wasp grubs. All cotton fields are well supplied with the wasps. 
