IXSECTS AND OTHER PARASITES. 203 



often impracticable. Then the tobacco stems can be 

 used by steeping one pound in five gallons of water, until 

 the water gets to be the color of strong tea. This liquid, 

 applied over and under the leaves with a syringe, will de- 

 stroy the insect quite as well as by fumigating, only in 

 either case the application should be made before the 

 insects are seen, to prevent their coming rather than to 

 destroy them when established ; for often by neglect they 

 get a foothold in such legions that all remedies become 

 ineffectual to dislodge them. Another means of prevent- 

 ing the green fly is to apply tobacco in the shape of dust, 

 or the sweepings of tobacco warehouses, which can be 

 found for sale in most seed or agricultural establish- 

 ments, at a cost of five to ten cents per pound. This, ap- 

 plied once or twice a week to an ordinary sized private 

 greenhouse, would effectually prevent any injury from 

 green fly. No special quantity of this need be prescribed, 

 as all that is necessary is to see that it is so dusted on 

 that it reaches all parts of the plant and on both sides of 

 the leaves. It it best to slightly syringe the plants be- 

 forehand, so that the dust will adhere to the leaves. 

 When applied to plants out-doors, it should be done in 

 the morning when the dew is on. Fruit-trees of many 

 kinds, shrubs, Roses of all kinds. Chrysanthemums, 

 and many other plants grown out of doors, are particu- 

 larly liable to injury from some species of Aphis ; but 

 the application of tobacco dust, if made in time, will be 

 found a cheap and effectual remedy. 



Ground or Blue Aphis is a close relative of the preced- 

 ing, but it gets its living from the roots down in the soil, 

 while the Green and Black Aphis feed in the air on the 

 leaves. The Blue Aphis attacks a great many varieties of 

 plants, particularly in hot, dry weather ; and whenever 

 Asters, Verbenas, Petunias, Centaureas, or such plants 

 begin to droop, it will be found on examination, in three 

 cases out of four, that the farthest extremities of their 



