CABBAGE WEB MOTH. 339 



# the body, while those unattacked had preserved the fresh color, 

 and the tail moved about readily ; the diseased ones becoming 

 stiff and more or less dried. Mr. Putnam thinks that at least 

 two-thirds of the chrysalids of this butterfly, hundreds of which 

 had in the early autumn suspended themselves about his house 

 and fences, had been attacked by these useful allies. 



On opening the body of the infested chrysalids I found about 

 thirty parasites in different stages of growth, in one case thirty- 

 two, in another only twelve. We can readily see how efficient 

 these minute insects become in reducing the numbers of their 

 hosts. A large proportion of the Pteromalus undoubtedly win- 

 ter over in the body of the chrysalis, the adult insects appear- 

 ing in the spring. In England Mr. Curtis found the fly in 

 June, so that evidently there is an autumn and spring brood of 

 flies. 



Another parasite is the larva of a parasitic fly, Tachina (Fig. 

 4, enlarged three times), the adult form of which 

 closely resembles the common house-fly. It is 

 a flattened, cylindrical maggot, both ends of 

 the body rounded much alike. The mouth- 

 parts are partly aborted, there being only two Larva of TaMna. 

 retractile horny mandibles by which the fatty portions of its 

 host is eaten. 



Besides this large Tachina I found a minute fly in the same 

 bottle with a number of the chrysalids of the butterfly, and am 

 inclined to think that it may have lived parasitically in them, 

 but would not be confident that it is so. It is a small black fly, 

 about a line in length, and with dark wings. 



The Cabbage Web Moth. — My attention was first called to 

 this moth, now almost cosmopolitan in its distribution, in Sep- 

 tember and October, 1870, at the Agricultural College at Amherst. 

 The little green caterpillars were quite abundant on the under 

 side of the outer leaves of the cabbages on the college farm, 

 and their web-like, delicate cocoons were found attached to the 

 leaf in depressions or folds. Afterwards a correspondent in 

 Michigan sent me specimens of the worm, the cocoon and moth, 

 stating that it was doing great damage to the cabbages there. 

 The season at Amherst, as all over New England in 1870, was 



