LOCUSTS AND GRASSHOPPERS (ACRIDIID&\ 125 



to fly at night when the weather is warm and the wind 

 favourable. This fact, in connection with the strong 

 probability, nay, certainty, that swarms frequently fly 

 at such a height as to be invisible in the daytime, will 

 alone account for their repeated sudden and mysterious 

 appearances in the morning, at other times in the after- 

 noon of bright clear days, in localities, when nothing 

 had been seen or heard of them along the line they had 

 come. It is possible they prefer nights when the moon 

 shines, though they are probably not confined to them ; 

 the warmth and wind being the influencing conditions. 

 Obviously, this point is an important item in determining 

 the possible distance to which single flights may extend. 

 Flying two clays and a night, say thirty hours, with a 

 moderately strong and long-continued wind, they may 

 pass over a distance of from four hundred and fifty to 

 five hundred miles, and more, before alighting. 



As evidence of the locusts' power of prolonged 

 flight, the fact that they traverse seas of considerable 

 width may be stated ; though the sea is undoubtedly 

 often a source of destruction of swarms. They have 

 been known to reach the Canary Isles from the African 

 coast ; to come into Cyprus from the neighbouring 

 coasts of Asia Minor ; to cross over the Red Sea. They 

 have been seen in the Balearic Isles, having come from 

 North Africa, and there are well-authenticated cases of 

 their occurrence at sea. On November 2, 1865, a 



