THE COMMON CABBAGE WORM. 9 
relation to the cabbage worm as does the ichneumon fly, and is there- 
fore beneficial, was first noticed in this country in 1869, evidently 
having been imported with the host. The eggs of this species are 
deposited in the cabbage worm, which, while completing its trans- 
formation to pupa, dies, and the parasites issue from the latter. 
Fic. 9—A chalcis fly, Pteromalus puparum, a parasite of the common cabbage worm: 
Female at left, male at right. Greatly enlarged. (Author's illustration.) 
Wasps, particularly certain paper wasps! and related forms, are 
also of great service in reducing the numbers of this and other 
cabbage worms, appearing to prefer them to other prey. 
The small, evil-smelling ambush-bug? (fig. 10) secretes itself in 
flowers, such as the thistle and goldenrod, and destroys numbers of 
butterflies, capturing them and 
sucking out their body fluids. 
Numerous other enemies* attack 
this cabbage worm, and it is some- 
times subject to a contagious bac- 
terial disease * similar to that of the 
cabbage looper. It is, however, less 
susceptible to this malady; although 
in some seasons, for example, In Pie0-—An ambush-bug, Phymata wolffi, 
1946.in southern Cylifornia, great © on eabbaze warm : a, View trom above: 
numbers are destroyed by it. b, view from side; c, front leg; d, beak. 
Birds which are known to feed a Re ae Sie nie Sages 
upon cabbage worms are the chip- 
ping sparrow, English sparrow, and house wren. It is certain, how- 
ever, that other species eat them, and in one case it was found that 
during the winter the number of pup of the cabbage butterflies was 
reduced more than 90 per cent by birds feeding upon them. 
1 Polistes metricus Say, pallipes Lepel., et al. 
°Phymata wolfii Stal. 
® Among other predacious enemies observed in this country are the wheel bug (Arilus 
cristatus lL.) and the armed soldier-bug (Podisus maculiventris Say). The cabbage worm 
is also parasitized by the tachina flies Hxorista vulgaris Fall and Frontina archippivora 
Will., as well as by Sarcophaga (Boettcheria) latisterna Parker. About 10 additional 
European parasites are listed. 
4 Micrococcus pieridis Burrill. 
