206 THE ENTOMOLOGIST. 
of their life-history than is afforded by the normal climate of 
Britain at that period of their existence, but seems also largely 
consequent on a corresponding increase of temperature on the 
Continent at the period of the flight of the imago; for it is 
undoubtedly the fact that the activity of the perfect insect is 
largely influenced by this condition, and the great distances 
which many of the large hawk-moths are capable of traversing 
have been attested by records of the capture of various species on 
board ships in mid-ocean [see Entom. 147.—Ep.]. Also among 
some species of Lepidoptera excessive multiplication, owing to 
local causes, has been observed to induce a migration of the 
imagines, probably in search of a less depastured district. 
The records of Irish Entomology, so far as they are available, 
seem to bear out the above opinion; for the sudden appearance 
of Colias edusa and Sphinx convolvuli, &c., in England, in such 
summers as that of 1885,is generally paralleled in Ireland by a 
corresponding phenomenon, but in a lesser numerical degree; but 
if a second hot season succeeds, very usually the first year’s 
migrants are found to reproduce themselves in such numbers 
that our fields and gardens are replenished to perhaps an equal 
degree with those of the more favourably situated island. 
These remarks, however, may seem to bear but little on the 
beautiful insect whose parochial settlement Mr. Salwey discusses. 
But, although it is very hard to believe, there seems good reason 
for maintaining that Deiopeia pulchella is an erratic species, and 
has some habit of migration which is very hard to account for in 
a lepidopteron of apparently such weak powers of flight. Possibly 
it has some power of sustaining a lengthened flight when carried 
upon a strong wind; for it has been taken, on one occasion at 
least, lately, far away in the Atlantic; and whether it flew the 
whole distance or was carried on the rigging of a ship, the fact 
remains that the imago has some habit which conduces to a wide 
distribution, whether by ship or railway train. In Central 
Europe its occurrence is, I believe, usually looked upon as 
sporadic; but in the southern countries, chiefly those on the 
Mediterranean coasts, or in islands such as Corsica, it breeds 
abundantly and constantly. This is also the case along the 
North coast of Africa and Sierra Leone; and it appears to have 
spread over a wide portion of the earth’s surface, chiefly such 
regions as enjoy a subtropical climate. 
