70 THE entomologist's eecord. 



of a light-house keeper on Lake Ontario, who, in 1885, reported that 

 he had been greatly annoyed by the large swarms of Anosia archippxis, 

 that flew against the lantern and obscured the light. 



But migrations of butterflies, so far as we know, 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 Voyaije round the world, Darwin Avrites : *' Several 

 times when the ship has been some miles off the mouth of the river 

 Plata, and, at other times, Avhen ofi' the shores of northern Patagonia, 

 we have been surrounded by insects. One evening, when Ave were 

 about ten miles from the Bay of San Bias, 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 

 [C'oZta.s leshici] very similar to, but not identical with, the common 

 English Col'ias cdum. Some moths and Hymenoptera accompanied 

 the butterflies, and a fine beetle (L'ahmima) 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 ofi" the land, but we must 

 conclude that they voluntarily took to flight. The great bands of the 

 Colias seem at first to afibrd an instance like those on record of the 

 migrations of another butterfly, Vanessa (ryrctweis) cardni; 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 ('(//(.srt, which is indirectly referred to in theprecedingparagraph, 

 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. From the north of England (sometimes even from the north 

 of Scotland) to the south, it is 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 difierent years. Fitch gives [Entom., xi., pp. 

 53-54) the following summary of the years in which the tAvo species of 

 Colias haA'e been abundant in this country : C. Ju/ale Avas common in 

 1821, 1826, 1828, 1835, 1842 (particularly so, but no C. ediisa seen), 

 1843 (many, also C. ednsa), 1844 (several, C. edum much the com- 

 moner, as in 1843), 1847, in 1849 there Avere a feAV, 1851 (one 

 record), 1855 (rare, C. edusa common), 1856 (tAvo records), 1857 (very 



