INSECTS INJURIOUS TO CABBAGE, ETC. 



323 



England there are three generations a season and there are prob- 

 ably five or six in the extreme South, as the butterflies there remain 

 on the wing all winter. 



Enemies. Fortunately, the parasites of the cabbage worm are 

 becoming very effective in checking its multiplication, and in 

 many sections of New England where it has existed the longest, 

 it rarely becomes very injurious, so well do the parasites control 

 it. Most of these are importations from Europe, one of the 

 most important being a small wasp-like Braconid fly (Apanteles 

 glomeratus Linn.) which was purposely imported from England 

 in 1883. During the autumn of 1904 Dr. Chittenden states that 



FIG. 272. Apanteles glomeratus, a parasite of the cabbage worm: a, adult 

 fly; 6, cocoon; c, flies escaping from cocoons natural size, a, 6, highly 

 magnified. (After Chittenden, U. S. Dept. Agr.) 



it killed practically every worm at Washington, D. C. The maggots 

 of these little parasites live within the worms and when full grown 

 come forth and spin masses of small white cocoons on the foliage, 

 often attached to the dead or dying worm (Fig. 272). Another 

 very important parasite is a minute Chalcis-fly (Pteromalus 

 puparum Linn.), about one-sixteenth of an inch long, which was 

 probably imported with its host. These often emerge in immense 

 numbers, hundreds of them often being secured from a single 

 worm. Wasps frequently prey on the caterpillars, using them for 

 provisioning their nests. Various predaceous bugs also attack 

 the worms as well as numerous other internal parasites. 



