562 



Quebracho Wood in Argentina. [dec, 



advantage that their leaves very quickly wither when their roots 

 are attacked, and this withering reveals the presence of the 

 grub. Regularly in the afternoon the plants should be gone 

 over, and those showing signs of withering pulled up and the 

 grubs taken out. The grubs will probably not be found at the 

 roots of completely withered plants, but will have moved to 

 others. 



5. The encouragement of birds and mammals that willingly 

 devour these pests, such as rooks, starlings, green plovers, night- 

 jars, owls, and black-headed and common gulls, bats and moles.. 



6. Insecticides. — There have been many experiments with a 

 view to killing the grubs by the injection into the soil of certain 

 insect-killing fluids, but little success has resulted. Great 

 interest was aroused some years ago by experiments that had 

 for their object the inoculation of the grubs with a disease- and 

 death-causing fungus, but the difficulties in the way of a proper 

 infection of the grubs are too great to allow of success. 



Among the countries which compete with the home produc- 

 tion of oak-bark are Argentina and Paraguay, which produce a 

 valuable wood, viz., the Quebracho, from 



Quebracho which tannin is obtained. In addition to 

 Wood 



in Argentina. producing tannin in its bark, like the oak, 

 chestnut, and other trees, it also contains, 

 like them, some in its sapwood, and stores it in a concentrated 

 state in considerable quantity in the whole of the central part of 

 the wood. According to Charpentier, its bark contains from 6 to 

 8 per cent, of tannin ; the sap, 3 to 4 per cent.; and the heart, 19 

 to 22 per cent. As the heart of the Quebracho represents two- 

 thirds and often three-quarters of the total quantity of wood, the 

 amount of tannin contained in this variety is considerable. It i s 

 inferior, however, to oak-bark taning material, and it contains 

 colouring matters which are difficult to separate. The impor- 

 tation of this wood, however, is probably one of the causes of 

 the present unremunerative price of English oak-bark. 



According to the Trade Returns of Argentina, the exports 

 are chiefly made in the form of wood or of Quebracho extract. 



