360 
DARWINISM 
CHAP. 
in Lat. 6° N., Long. 22|° W., being between the former position 
and Sierra Leone, thus rendering it probable that the moths 
came from that part of the African coast, in which case the 
swarm encountered by the Pleione must have travelled more 
than 1200 miles. 
A similar case was recorded by Mr. F. A. Lucas in the 
American periodical Science of 8th April 1887. He states 
that in 1870 he met with numerous moths of many species 
while at sea in the South Atlantic (Lat. 25° S., Long. 24° W.), 
about 1000 miles from the coast of Brazil. As this position 
is just beyond the south-east trades, the insects may have been 
brought from the land by a westerly gale. In the Zoologist 
(1864, p. 8920) is the record of a small longicorn beetle which 
Hew on board a ship 500 miles oft’ the west coast of Africa. 
Numerous other cases are recorded of insects at less distances 
from land, and, taken in connection with those already given, 
they are sufficient to show that great numbers must be con¬ 
tinually carried out to sea, and that occasionally they are able 
to reach enormous distances. But the reproductive powers of 
insects are so great that all we require, in order to stock a 
remote island, is that some few specimens shall reach it even 
once in a century, or once in a thousand years. 
Insects at great Altitudes. 
Equally important is the proof we possess that insects are 
often carried to great altitudes by upward currents of air. 
Humboldt noticed them up to heights of 15,000 and 18,000 
feet in South America, and Mr. Albert Muller has collected many 
interesting cases of the same character in Europe. 1 A moth 
(Plusia gamma) has been found on the summit of Mont Blanc ; 
small hymenoptera and moths have been seen on the Pyrenees 
at a height of 11,000 feet, while numerous flies and beetles, 
some of considerable size, have been caught on the glaciers 
and snow-fields of various parts of the Alps. Upward 
currents of air, whirlwinds and tornadoes, occur in all parts 
of the world, and large numbers of insects are thus carried 
up into the higher regions of the atmosphere, where they 
are liable to be caught by strong winds, and thus conveyed 
enormous distances over seas or continents. With such 
1 Trans. Ent. Soc., 1871, p. 184. 
