244 TRANSACTIONS OF THE ILLINOIS 



Philadelphia and Washington. In 1869 it was reported as common in 

 New Jersey, though Dr. Fitch states that it was first seen in Eastern New 

 York in 1870. By 187 1 it had traveled as far eastjvard as Halifax, Nova 

 Scotia, and westward to Central New York, It must have reached 

 Illinois about 1876, making its first appearance in the vicinity of Chicago, 

 altliough attracting no attention until 1877, so far as I can ascertain, 

 when it was found at Maplewood, west of Chicago, in September, having 

 reached this point in its westward march. In 1878 it made its appear- 

 ance in injurious numbers as far south in the State as Springfield, and a 

 few specimens were taken at Carbondale. Its general spread over the 

 State during the past season has already been referred to. What point it 

 has reached in its westward march I have not learned, but it is more than 

 probable that by this time it has passed across Iowa. 



It was probably introduced into this country in some vessel which 

 discharged its cargo at Quebec. Prof. Riley, in his second report on the 

 Noxious Insects of Missouri, says it was probably introduced in the egg 

 state, on a batch of refuse cabbage leaves which were thrown from some 

 vessel, where, after hatching, the young larvje managed to find suitable 

 food close by. Dr. Fitch, in commenting on this suggestion, remarks: 



The insect does not remain in its egg state the length of time required for such a 

 voyage. The eggs, however, hatching on shipboard, the worms from them would 

 readily sustain themselves on the leaves, and on reaching port, where fresh vegetables 

 could be obtained, the few wilted and decaying cabbages remaining would be thrown 

 away, with some of these worms lurking among the leaves, whereby their race was 

 probably started on our continent. 



As this species has been known in Europe from time immemorial, it 

 is a matter of surprise that it was not introduced at an earlier day. But 

 this is to be accounted for by the fact that it was necessary a combination 

 of a number of favorable circumstances should take place before it would 

 be successfully transferred from one continent to another. 



Dr. Fitch mentions a somewhat singular fact observed at its intro- 

 duction into the section of New York in which he resides: 



During the fore part of the year 1870 our white butterfly [Pieris oleracea) made 

 its appearance in the usual manner. One or more of them might be seen almost every 

 day of August. Four white butterflies were hovering about and alighting around me 

 in my garden, when one of them was noticed, with much surprise, as having a round 

 black spot near the middle of its fore wings. Conjecturing it to be the spotted variety 

 of our white butterfly, and anxious to secure the specimens, I hastened to obtain a net 

 for its capture; but on being approached, to my great regret, it flew wildly away. Next 

 day, however, two similar specimens were noticed and captured, and on examination 

 were discovered to be the European Pieris rapce. And on the following days these 

 spotted butterflies occurred more and more common, whilst our white butterfly imme- 

 diately vanished, not one of them being seen either in the gardens or the meadows. 



A somewhat similar result has attended their appearance in my 

 immediate neighborhood. 



Our native species — Pieris protodice — is usually very abundant 

 during the summer and early part of the fall. Last fall, as before stated, 

 a few specimens of the European species were observed, the native species 



