70 THE ENTOMOLOGIST’S RECORD. 
| 
of a light-house keeper on Lake Ontario, who, in 1885, reported that | 
he had been ereatly annoyed by the large swarms of Anosia a1 ‘chippus, — 
that flew against the lantern and obscured the light. 
But migrations of butterflies, so far as we ‘snow, do not usually 
take place by night. They are children of the sun, their movements 
are readily observed, and their migrations have been recorded by many 
naturalists. In his Voyaye round the world, Darwin writes: ‘ Several 
times when the ship has been some miles off the mouth of the river 
Plata, and, at other times, when off the shores of northern Patagonia, 
we have been surrounded by insects. One evening, when we were 
about ten miles from the Bay of San Blas, vast numbers of butterflies, 
in bands or flocks of countless myriads, extended as far as the eye 
could range. Even by the aid of a telescope it was not possible to see 
a space free from butterflies. The seamen cried out that it was 
‘snowing’ butterflies, and such, in fact, was the appearance. More 
species than one were present, but the main part belonged to a kind 
[Colias lesbia] very similar to, but not identical with, the common 
English Colizs edusa. Some moths and Hymenoptera accompanied 
the butterflies, and a fine beetle (Calosoma) flew on board. Other 
instances are known of this beetle having been caught far out at sea, 
and this is the more remarkable, as the great number of the Carabidae 
seldom or never take wing. ‘The day had been fine and calm, and the 
one previous to it equally so with light and variable airs. Hence we 
cannot suppose that the insects were blown off the land, but we must 
conclude that they voluntarily took to flight. The great bands of the 
Colias seem at first to afford an instance like those on record of the 
migrations of another butterfly, Vanessa (Pyrameis) cardi; but the 
presence of other insects makes the case distinct and even less intellig- 
ible. Before sunset, a strong breeze sprung up from the north, and 
this must have caused tens of thousands of the butterflies and other 
insects to have perished.” 
Colias edusa, which is indirectly referred to in the preceding paragraph, 
is one of the best-known of our British immigrant species. Equally 
uncertain and sporadic, also, is the appearance of its relative, C. hyale, 
in Britain. Sometimes, for many years together, neither species of 
these butterflies will be seen. Then will come a year, when, in May 
or early June, one or both of the species makes its appearance in large 
numbers. rom the north of England (sometimes even from the north 
of Scotland) to the south, itis then to be met with, wherever a clover or 
lucerne field is to be found, although, as might be expected, the 
southern counties get the more frequent visits and the greater number 
of visitors. Occasionally the two kinds will appear in the same year. 
They did so in 1835, 1857, 1868, 1875, 1876, and 1892, when both 
insects were in great abundance. On a few other occasions, during — 
the century, when one species has been abundant, the other has also 
occurred, but more sparingly, although, usually, their seasons of 
abundance occur in different years. Fitch gives (ntom., xi., pp. 
58-54) the following summary of the years in which the two species of 
Colias have been abundant in this country: C. hyale was common in 
1821, 1826, 1828, 1835, 1842 (particularly so, but no C. edusa seen), 
1843 (many, also C. edusa), 1844 (several, C. edusa much the com- 
moner, as in 1843), 1847, in 1849 there were a few, 1851 (one 
record), 1855 (rare, CU. edusa common), 1856 (two records), 1857 (very 
