Dragon- Fly Storms. 131 



that they appear only when flying before the south- 

 west wind, called pampero the wind that blows 

 from the interior of the pampas. The pampero 

 is a dry, cold wind, exceedingly violent. It bursts 

 on the plains very suddenly, and usually lasts only 

 a short time, sometimes not more than ten minutes ; 

 it comes irregularly, and at all seasons of the year, 

 but is most frequent in the hot season, and after 

 exceptionally sultry weather. It is in summer and 

 autumn that the large dragon-flies appear ; not with 

 the wind, but and this is the most curious part of 

 the matter in advance of it ; and inasmuch as 

 these insects are not seen in the country at other 

 times, and frequently appear in seasons of pro- 

 longed drought, when all the marshes and water- 

 courses for many hundreds of miles are dry, thev 

 must of course traverse immense distances, flying 

 before the wind at a speed of seventy or eighty miles 

 an hour. On some occasions they appear almost 

 simultaneously with the wind, going by like a flash, 

 and instantly disappearing from sight. You have 

 scarcely time to see them before the wind strikes 

 you. As a rule, however, they make their appear- 

 ance from five to fifteen minutes before the wind 

 strikes ; and when they are in great numbers the 

 air, to a height of ten or twelve feet above the 

 surface of the ground, is all at once seen to be full 

 of them, rushing past with extraordinary velocity 

 in a north-easterly direction. In very oppressive 

 weather, and when the swiftly advancing pampero 

 brings no moving mountains of mingled cloud and 

 dust, and is consequently not expected, the sudden 

 apparition of the dragon-fly is a most welcome one, 



