When taken in the hand, it has the habit, common to most grasshoppers, of pouring out an inky fluid from its mouth; only the discharge is unusually copious in this species. It has another habit in defending itself which is very curious. When captured it instantly curls its body round, as a wasp does to sting. The suddenness of this action has more than once caused me to drop an insect I had taken, actually thinking for the moment that I had taken hold of a wasp. Whether birds would be deceived and made to drop it or not is a question it would not be easy to settle; but the instinct certainly looks like 'one of a series of small adaptations, all tending to make the resemblance to a wasp more complete and effective.
One of the most curious things I have encountered in my observations on animal life relates to a habit of the larger species of dragon-flies inhabiting the Pampas and Patagonia. Dragon-flies are abundant throughout the country wherever there is water. There are several species, all more or less brilliantly coloured. The kinds that excited my wonder, from their habits, are twice as large as the common widely distributed insects, being three inches to four inches in length, and as a rule they are sober-coloured, although there is one species--the largest among them--entirely of a brilliant scarlet. This kind is, however, exceedingly rare. All the different kinds (of the large dragon-flies) when travelling associate together, and occasionally, in a flight composed of countless thousands, one of these brilliant-hued individuals will catch the eye, appearing as conspicuous among the others as a poppy or scarlet geranium growing alone in an otherwise flowerless field. The most common species--and in some cases the entire flight seems to be composed of this kind only--is the Aeschna bonariensis Raml, the prevailing colour of which is pale blue. But the really wonderful thing about them all alike is, that they appear only when flying before the southwest 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 prolonged drought, when all the marshes and watercourses for many hundreds of miles are dry, they 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 appearance 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, for then an immediate burst of cold wind is confidently looked for. In the expressive vernacular of the gauchos the large dragon-fly is called _hijo del pampero_--son of the south-west wind.