THE VOYAGE OF THE BEAGLE 349 



us at a rate of ten or fifteen miles an hour. The main body 

 filled the air from a height of twenty feet, to that, as it ap- 

 peared, of two or three thousand above the ground ; " and the 

 sound of their wings was as the sound of chariots of many 

 horses running to battle:" or rather, I should say, like a 

 strong breeze passing through the rigging of a ship. The 

 sky, seen through the advanced guard, appeared like a mezzo- 

 tinto engraving, but the main body was impervious to sight; 

 they were not, however, so thick together, but that they 

 could escape a stick waved backwards and forwards. When 

 they alighted, they were more numerous than the leaves in 

 the field, and the surface became reddish instead of being 

 green : the swarm having once alighted, the individuals flew 

 from side to side in all directions. Locusts are not an un- 

 common pest in this country : already during the season, sev- 

 eral smaller swarms had come up from the south, where, as 

 apparently in all other parts of the world, they are bred in 

 the deserts. The poor cottagers in vain attempted by light- 

 ing fires, by shouts, and by waving branches to avert the 

 attack. This species of locust closely resembles, and perhaps 

 is identical with, the famous Gryllus migratorius of the East. 

 We crossed the Luxan, which is a river of considerable 

 size, though its course towards the sea-coast is very imper- 

 fectly known: it is even doubtful whether, in passing over 

 the plains, it is not evaporated and lost. We slept in the 

 village of Luxan, which is a small place surrounded by gar- 

 dens, and forms the most southern cultivated district in the 

 Province of Mendoza; it is five leagues south of the capital. 

 At night I experienced an attack (for it deserves no less a 

 name) of the Benchuca, a species of Reduvius, the great 

 black bug of the Pampas. It is most disgusting to feel soft 

 wingless insects, about an inch long, crawling over one's 

 body. Before sucking they are quite thin, but afterwards 

 they become round and bloated with blood, and in this state 

 are easily crushed. One which I caught at Iquique, ( for they 

 are found in Chile and Peru,) was very empty. When placed 

 on a table, and though surrounded by people, if a finger was 

 presented, the bold insect would immediately protrude its 

 sucker, make a charge, and if allowed, draw blood. No pain 

 was caused by the wound. It was curious to watch its body 



