390 INSECTS "AFFECTING VEGETATION 



Some practical experience is necessary to fumigate successfully, 

 and it will therefore rarely be wise for anyone to undertake it on a 

 large scale without having made preliminary experiments. 



Bisulphid of Carbon Vapor. In line with the use of hydro- 

 cyanic-acid gas is the employment of the vapor of bisulphid of 

 carbon to destroy insects on low-growing plants, such as the aphides 

 on melon and squash vines. The treatment, as successfully prac- 

 ticed by Professors Garman and Smith, consists in covering the 

 young vines with small tight boxes 12 to 18 inches in diameter, of 

 either wood or paper, and introducing under each box a saucer con- 

 taining one or two teaspoonfuls (1 or 2 drams) of the very volatile 

 liquid bisulphid of carbon. The vines of older plants may be 

 wrapped about <the hill and gathered in under larger boxes or tubs, 

 and a greater, but proportional, amount of the liquid used. The 

 covering should be left over the plants from three-quarters of an 

 hour to an hour, and with 50 to 100 boxes a field may be treated 

 with comparative rapidity. 



Bisulphid of carbon has proved also to be the most effective 

 means of disinfecting grape cuttings suspected of being infested with 

 phylloxera. The cuttings are inclosed in a tight barrel or fumi- 

 gating box, and the bisulphid of carbon, poured out in a shallow 

 dish, is put on top of the cuttings. An ordinary saucerful of the 

 chemical is enough for a box 3 feet cube. The treatment lasts from 

 forty-five to ninety minutes. This is a pretty strong fumigation, 

 but the dormant condition of the cuttings makes this possible. 



REMEDIES FOR SUBTERRANEAN INSECTS. 



Almost entire dependence is placed on the caustic washes, or 

 those that act externally, for insects living beneath the soil on the 

 roots of plants, including both sucking and biting insects, prominent 

 among which are the white grubs, maggots in roots of cabbage, 

 radishes, onions, etc., cutworms, wire worms, apple and peach root- 

 aphides, the grape phylloxera, and many others. 



The insecticide must be one that will go into solution and be 

 carried down by water. Of this sort are the kerosene emulsions and 

 resin wash the former preferable the potash fertilizers, muriate 

 and kainit, and bisulphid of carbon. The simple remedies are 

 applications of strong soap or tobacco washes to the soil about the 

 crown; or soot, ashes, or tobacco dust buried about the roots; also 

 similarly employed are lime and gas lime. Submersion, wherever 

 the practice of irrigation or the natural conditions make it feasible, 

 has proved of the greatest service against the phylloxera. 



Hot Water. As a means of destroying root-aphides, and par- 

 ticularly the woolly aphis of the apple, the most generally recom- 

 mended measure hitherto is the use 01 hot water, and this, while 

 being both simple and inexpensive, is thoroughly effective, as has 

 been demonstrated by practical experience. Water at nearly the 

 boiling point may be applied about the base of young trees without 

 the slightest danger of injury to the trees, and should be used in 

 sufficient quantity to wet the soil thoroughly to a depth of several 

 inches, as the aphides may penetrate nearly a foot below the surface. 



