MIGRATIONS OF INSECTS. 273 



destination, and are said seldom to turn out of their 

 way, on account of intervening obstacles, and even 

 if they encounter a lofty wall or a house, they will 

 attempt to scale it ; but when they meet with a river 

 they follow the course of the stream, as if instinc- 

 tively aware that it will ultimately lead them to the 

 sea, as was probably the case with the African 

 locusts, mentioned by Jackson. These multitudinous 

 hordes of crabs, however, do not perish in the sea, 

 but go there to spawn ; though from this spawn 

 forming a rich banquet for the sea-fish, the provi- 

 dential effect is nearly the same as in the instances 

 of locusts, aphides, lady-birds, and saw-flies. 



Some of the more remarkable migrations of in- 

 sects are, in the same way, for the purpose of de- 

 positing their eggs, or disposing of their supernu- 

 merary progeny in suitable localities, in the case, 

 for example, of ants and bees. Kirby and Spence 

 have given the following animated and eloquent 

 account of the migrations of the former. ' In the 

 warm days that occur from the end of July to the 

 beginning of September, and sometimes later, the 

 habitations of the various species of ants may be 

 seen to swarm with winged insects, which are the 

 males and females, preparing to quit for ever the 

 scene of their nativity and education. Every thing 

 is in motion — and the silver wings, contrasted with 

 the jet bodies which compose the animated mass, 

 add a degree of splendour to the interesting scene 

 The bustle increases, till at length the males rise, as 

 it were by one general impulse, into the air, and 

 the females accompany them. The whole swarm 

 alternately rises and falls, with a slow movement, 

 to the height of about ten feet, the males flying ob- 

 liquely, with a rapid zig-zag motion, and the females, 

 though they follow the general movement of the 

 column, appearing suspended in the air, like bal- 



