MIGRATION AND DISPERSAL OF INSECTS: LEPIDOPTERA. 185 
beginning of September, pass the winter in the south, and then return 
northward in the early spring to deposit their eges for the summer’s 
brood, it would give them a much longer active life in the mature 
state, than falls to the lot of butterflies that hybernate in this region. 
Whether any of those passing the winter in the south, reach the far 
north the following season, is yet open to question.’ Without 
discussing the doubtful logic of the first of these quotations, except to 
say that, even if we believed the species did actually reach the south, 
where it could hybernate, after leaving the northern regions where 
the autumnal examples were born, we do not understand why it must 
of necessity return ‘‘in spring, by scattered individuals,’ and we would 
ask whence, if not from those ‘‘ passing the winter in the south,’ Moffat 
surmises those that ‘‘reach the far north the following season ’’ do 
come. Possibly he believes that not the original emigrants themselves 
but their progeny reach so far north. The analogy of Pyrameis cardut, 
Colias edusa, C. hyale, and other migrating Palearctic species, leads us 
to suspect that it is the emigrants that reach to the northern limit of 
the range of the species. It may be well now to consider in some 
detail the observations relating to the autumnal swarms of this insect 
that have given rise to the view that a return journey is eo nae 
Saunders reports (Canadian Entomologist, 1., pp. 156-157) that 
on September 1st, 1871, while driving along the Lake Shore Road, on 
the borders of Lake Erie, a mile or two south of Port Stanley, some 
groups of A. archippus, numbering probably hundreds of individuals, 
which had rested at night on the trees adjoining the hotel at Port 
Stanley, were gyrating in a wild manner at all heights, some so far up 
that they appeared but as moving specks in the sky, others floating 
lower, over the tops of the trees, in an apparently aimless manner. 
At about nine o’clock the same morning, however, passing a group of 
trees forming a rude semicircle at the edge of a wood facing the lake, 
the leaves of the trees attracted attention. They seemed possessed of 
unusual motion, and displayed fitful patches of brilliant red. On 
alightine, a nearer approach revealed the presence of vast numbers—I 
might safely say millions—of these butterflies clustering everywhere. 
When disturbed, they flew up in immense numbers, filling the air, 
and after floating about a short time gradually settled again. There 
appeared to be nothing on the trees to attract them. Reed observes 
(loc. cit., 1., p. 19) that in 1868 the species literally swarmed at 
Amherstburg, reminding him ofa similar occurrence in Toronto about 
seven years previously. Peabody notes (doc. cit., xil., pp. 119-120) 
that at Racine, Wisconsin, during the first week of September, 1868, 
A. archippus appeared in oreat numbers and gathered in several 
swarms about trees in the vicinity. The day was cloudy, but without 
rain. Shortly after noon the swarms seemed to gather and settle 
upon an oak tree in the garden, the southern aspect of which they 
covered to such an extent that the green of the leaves was quite 
obscured by the brown of the wings of the butterflies. They remained 
until after nightfall, but were gone in the morning. Another observer 
on September 19th, 1868, reports that at St. Joseph, Missouri, he saw 
“millions of these butterflies (A. archippus) filling the air to a height 
of three or four hundred feet for several hours, and flying from north 
to south.’ Thaxter writes (doc. cit., xil., p. 38) that while spending the 
winter of 1875-1876 in Apalachicola, Viovida, he found a swarm of 
