MIGRATIONS OF INSECTS. 271 



bodies. By what instinct/' he adds, " do these crea- 

 tures undertake this dangerous flight ? Is it riot the 

 wise institution of the Creator to destroy a dreadful 

 plague to the country*?" We think that it is more 

 consistent with other instances of extensive destruc- 

 tion among particular species to refer it to the design 

 of Providence to furnish food for carnivore us animals. 

 The day-flies (Ephemeridce), for example, are a 

 harmless race, and yet the numbers of them which 

 perish only a few hours after they acquire wings is 

 scarcely inferior to those of the locusts t- Like 

 the locusts, too, they chiefly perish in the water, both 

 affording an abundant banquet for the fishes. 



There is one circumstance in these migrations, 

 which is remarked by most observers, that appears 

 to corroborate these views ; we refer to the direction 

 commonly taken by them being towards the sea, and 

 their pursuing their course with little deviation. The 

 locusts seen by Captains Irby and Mangles, on the 

 southern shore of the Dead Sea, were said to be on 

 their way to Gaza, to which they pass almost an- 

 nually J; those observed in Barbary by Dr. Shaw 

 " marched directly towards the sea ;" and Hassel- 

 quist tells us they seldom or never deviate from the 

 direction of their course. These very singular facts 

 are strikingly illustrated by the migrations of a much 

 larger, though it would appear no less destructive 

 animal, the lemming rat (Mus lemmus, LINN.), 

 which inhabits the north of Europe, and lives on 

 vegetable food. The migrations of the lemming take 

 place at uncertain intervals of about ten years, from 

 Lapland towards the southern parts of Sweden, 

 induced, it is supposed, by the foresight of a severe 



* Has=elquist's Voyage, p. 444. 



j- See Insect Transformations, pp. 218 and 373. 



J Travels in Egypt and Syria, 443. 



Travels, 287. 



