A Trip to Tucuman 279 



result of the expedition was not wholly satisfactory so 

 far as the number of specimens was concerned. I had 

 an opportunity, however, to observe some things which 

 w r ere not devoid of interest. A great swarm of grass- 

 hoppers were at work in a field through which I rambled. 

 The langustos, as the natives call them, were fully 

 mature, and were busy devouring the herbage. The 

 day was quite still, and it was a novel thing to hear the 

 sound which they produced as they fed upon the grasses 

 and foliage. The working of thousands upon thousands 

 of small jaws and the rustling of wings, and the stir 

 they made as they crawled over the ground, filled the 

 air with a low but continuous murmur, unlike anything 

 else I have heard. It became impressive as evidence 

 of the fact that so small and insignificant a thing as a 

 grasshopper may indeed become : 'a burden,' and a 

 great burden, too, to the land. The species (Schisto- 

 cerca paranensis) is at times a veritable scourge, as 

 great as that of the locusts of the Orient, even more 

 so than the common Melanoplus spretus, the Rocky 

 Mountain Locust, to which it is not distantly related. 

 The insects were being greedily devoured by birds, and 

 I noted that the Guira was doing its part in destroying 

 them. By the roadside I had a good opportunity to 

 examine the nest of an Oven-bird (Furnarius rufus) . It 

 was built low down on the branch of a tree, so that by 

 standing up in the carriage I could get a very good view 

 of it. I had seen the birds on the grounds of the Obser- 

 vatory at La Plata, and had often observed their nests 

 at a distance, but here was a chance to carefully study 

 one near at hand. The structure is almost globular in 

 outline, built of clay, about a foot in diameter, with an 

 entrance at one side. It is said that this entrance is 

 always placed by the bird toward the rising sun. 



