XII MIGRATION OF LOCUSTS 295 



Natural History of these Insects. The South African species mani- 

 fests the gregarious and migratory disposition when the individuals 

 are quite young, so that they travel in flocks on foot, and are called 

 by the Dutch " Yoetgangers." After hatching, the various families 

 of young amalgamate, so that enormous numbers come together. 

 Having denuded the neighbourhood of all its food-supplies, they 

 move off in search of fresh crops and pastures new. They take advan- 

 tage of roads, and sometimes a good many miles will be traversed in 

 a day; they proceed by means of short leaps, rapidly repeated. When 

 the " Yoetgangers " are thus returning northwards towards the 

 lands in the interior from which their progenitors departed, no 

 obstacles can stay their course. Forests or rivers may intervene, 

 diverting them for a while from their line of march, but they 

 succeed ultimately in continuing their journey to the interior. 



The manner in which these wingless locusts occasionally cross 

 broad rivers is interesting, as it has some bearing on the 

 difficult question of the possibility of winged locusts crossing seas 

 of considerable width. Mrs. Barber refers to an instance that 

 took place on the Vaal Eiver in the spring of the year 1871, 

 shortly after the discovery of the Diamond-fields. The country 

 was at that time swarming with young locusts ; every blade of 

 grass was cleared off by them. One day a vast swarm of the 

 " Yoetgangers " made their appearance on the banks of the Yaal 

 Eiver ; they appeared to be in search of a spot for crossing, 

 which they, could not find, the river being somewhat swollen. 

 For several days the locusts travelled up the stream ; in the 

 course of doing this they paused for some time at an abrupt 

 Ijend in the river where a number of rocks were cropping out, 

 as if in doubt whether to attempt a passage at this place. They, 

 however, passed on, as if with the hope of finding a better ford ; 

 in this apparently they were disappointed, for three days after- 

 wards they returned to the same bend of the river, and there 

 plunged in vast multitudes into the stream, where, assisted by a 

 favourable current and the sedges and water-plants which grew 

 upon the projecting rocks, they managed to eftect a crossing, 

 though great numbers were drowned and carried away by the 

 flooded river. Mrs. Barber adds that " Yoetgangers " have l^een 

 known to attempt the passage of the Orange Eiver when it was 

 several hundred yards in breadth, pouring their vast swarms into 

 the flooded stream regardless of the consequences, until they 



