THE CHACO 393 



partments of the Province of Mendoza, a great invasion 

 of Isocas (larvae of a lepidopteran) and in various inspections 

 which I realized in the infected countryside I was able to 

 confirm that a number of birds occupied themselves in eat- 

 ing the larvae and adults of these Isocas (Colias lesbia Fabr.) 

 and among them Molothrus bonariensis predominated. 



"It is also a voracious destroyer of the white worm (larva 

 of Ligyrus bidentulus Fairm.) when these are exposed in 

 ploughing furrows in the vineyards. The 'bicho de cesto' 

 (JEceticus platensis Berg) is also very much persecuted by 

 the bird with which we are occupied. 



"The corn-fields suffer damages by reason of Molothrus 

 bonariensis, but only during the period between the be- 

 ginning of the ripening of the ear and its collection; cer- 

 tainly, one ought not to take this damage into considera- 

 tion when, during eleven months, Molothrus bonariensis 

 has fed in the cultivated country on other products, not 

 on maize, and among these has predominated the larva 

 of Chloridea armigera, the most formidable enemy of the 

 maize-fields. 



"I have examined the stomach contents of more than 

 sixty specimens of Molothrus bonariensis, freshly shot, in 

 the various seasons and have encountered about 90 per 

 cent of substance of animal origin and the rest grains, 

 principally maize, but the maize they have generally ob- 

 tained from the offal of horses and mules, as in Mendoza 

 a good deal of maize is given to working animals, and, as 

 the grain is fed entire, a goodly percentage of it is eliminated 

 without having been digested. It is for this reason that 

 one frequently finds this bird scratching among and turning 

 over the offal. This custom is why it has been given the 

 name of virabosta in Brazil. Therefore, Molothrus bona- 

 riensis may be looked upon as a bird helpful rather than 

 destructive to agriculture." 



Rice is planted in "boxes" about twenty-five feet square. 

 Water is supplied through a system of canals some of which 

 are many miles long, and its level is regulated by sets of 



