THE CABBAGE BUTTERFLY. 



337 



Fiq. 3. 



has been fearfully abundant in gardens in Eastern Massachu- 

 setts. "Were it not for the ichneumon 

 parasite (Fig. 3, a, male ; b, female ; 

 c, larva ; d, pupa), which has been 

 found to prey upon it very extensively, 

 the cultivation of the cabbage would 

 have to be given up in some districts. 

 This invaluable ichneumon is one of 

 the Chalcid family, and is the Ptero- 

 malus puparum of Linnaeus. It is 

 well known that the cabbage cater- 

 pillar (Pieris rapes) was introduced 

 into this country about the year 1857. 

 I had supposed that the parasite had 

 perhaps been imported with its host, 

 but now find that it is undoubtedly a j 

 native of this country as well as Eu- 

 rope. Having been 'favored by Mr. 

 Francis Walker with specimens of 

 both sexes from England, labelled by 

 him Pt. puparum, I found that our Parasite of the Ir $%? d ***• BuU 

 specimens did not differ specifically. Further, Mr. Walker 

 wrote me that there were specimens of the same species in the 

 British Museum taken in Hudson's Bay territory in 1844. Dur- 

 ing the past summer Mr. P. S. Sprague sent me specimens which 

 had been raised from the Rape Caterpillar in Vermont. Mr. J. A. 

 Lintner has also published a note in the "American Naturalist" 

 stating that he had reared this parasite from the same kind of 

 caterpillar, and previously to this Mr. S. H. Scudder had re- 

 ceived numerous specimens from Mr. A. G. T. Ritchie of Mon- 

 treal, Canada, who, if I understand his letter aright, first observed 

 these chalcids upon the cabbage leaves in July, 1870, when the 

 caterpillars were abundant. On the 23d of August of the same 

 year he had some of the parasites hatch out. To Mr. Ritchie, 

 then, is due the credit of being the first to make known the his- 

 tory of this invaluable insect. 



So that the parasite seems to cover even a wider field than its 

 host, and probably preys on our native cabbage butterfly, the 

 Pieris oleracea, as in Europe it preys on Pieris brassicce, the 

 caterpillar so destructive to the cabbage there. 



43 



