20 ENTOMOLOGICAL SOCIETY 
been added to that published by me in 1881, but its occurrence 
in such numbers, and over so large an extent of country, so soon 
after its first injuries were reported, presents abundant cause for 
reflection and would indicate that the species is rapidly extending 
its range, especially westward. 
Another species of the same genus, namely, P. nigrirostris. 
has been found in Canada by Mr. Jas. Fletcher, of Ottawa, also 
feeding upon clover. 
Pulvinaria innumerabilis was unusually abundant in 1884 in 
all parts of the country. There is need of very careful study of 
the forms found upon so many different trees, forms which, on 
account of their general resemblance, are looked upon as being 
one and the same species. So far as experiments go, some which 
I made some 12 years since at Kirkwood, Mo., by transferring 
the young from one plant to another, prove, so far as such evi- 
dence is proof, that the species found upon Oak, Maple and 
Grape-vine are the same ; but where such evidence is wanting, 
we must study not only the young and the males but the struc- 
tural characteristics, especially those of the anal plate in the 
females, before we can feel assured that we have to deal with but 
one species. 
That cosmopolitan butterfly Pyrameis cardui attracted con- 
siderable attention during the year, feeding upon our nettles and 
thistles. I refer to it, however, chiefly because of its migrations, 
notices of which have been abundant in European journals. The 
fact of the extended migration of butterflies has only recently 
come to be fully appreciated. I have discussed these butterfly 
migrations, so far as our Danais archippus is concerned, in an 
article in the Scientific American for April 6th, 1878, entitled 
" The Migration of Butterflies," and shown that there is a very 
general southward movement, accompanied by congregation and 
concentration, from the extreme northwestern portion of the 
country to the Gulf States in autumn, and a return migration and 
dispersion the ensuing spring and summer. 
It is a note worthy fact that migrating butterflies have a wide range. 
That Pyrameis cardui flies in vast numbers over large stretches 
of the European Continent and across the Channel to the British 
Isles is a well-established fact, and the migratory tendencies have 
their explanation, in all probability, in the same promoting 
