No. 6. DEPARTMENT OF AGRICULTURE. 796 



The most common plan in practice towards destroying them is by 

 fumigation, which meaias, in this case, to burn tobacco stems, which 

 may be obtained in bales from the seed stores which keep same io 

 stock for the convenience of customers. 



The process of burning is as follows: A small bunch of dry paper or 

 shavings, with a few dry stems to give the same a start, is placed at 

 the bottom of a can made for the purpose, with a perforated base to 

 cause the requisite draft, then the stems, with which the can is filled, 

 and which are expected to do the eflective plant-lice killing, before the 

 light is applied, should be a triiie dampened; by this means flaming 

 is avoided, which should never be allowed, as the hot flame with the 

 deleterious gases generated under those conditions are likely to do 

 serious injury to many tender plants which may be within the struc- 

 ture operated upon, as Heliotrope, Mignonette, and some other 

 plants. When the tobacco stems are not too damp to burn, yet too 

 damp to flame, they are just in the proper condition to produce the 

 smoke — the nicotine fumes — which suffocates our plant-enemy, the 

 green fly. 



Tobacco dust, when not too fine, may be used also for fumigating 

 purposes, and is put into operation by placing the material upon 

 plain paper in a perfectly dry spot on the floor of the greenhouse, and 

 with a few drops of petroleum ("coal-oil") at one end of the pile of 

 tobacco dust, then with a lighted match, touch the spot whereon are 

 the drops of oil, when it may then be allowed to burn until entirely 

 consumed, as no harm to the plants will result. 



Paper steeped in a solution of saltpetre (potassium nitrate) and 

 dried is also used upon which to place tobacco dust and burn. In 

 this case no petroleum oil is needed; by touching the prepared paper 

 with a light the combustion of both tobacco and paper is complete, 

 and without flame. 



There is also what is known as Aphis Punk on the market, a pe- 

 culiarly prepared paper, which is hung on wire in convenient places 

 in the greenhouse, and when lighted, is allowed to burn. This must 

 not be allowed to flame either, or similar damage before referred to 

 is likely to result. 



There are also a variety of liquids much in use nowadays, where 

 nicotine or the extract of tobacco forms the base and principal part 

 of this class of insecticides. Sometimes these liquids when reduced 

 to the proper degree of solution are applied directly to the plants 

 troubled with insects, by spraying. Another plan frequently in use 

 is when the liquid is placed in some convenient vessel and hot irons 

 are dropped therein, filling the atmosphere full of the insect death 

 dealing vapor. Some of the more advanced florists are using an 

 evaporating pan which is attached to the heaticg pipes; the liquid 

 is placed in the pans and in due course is evaporated into the at- 



