40 INSECTS INJURIOUS TO VEGETABLES 



ciucniriccjoUum. It was carefully tested years ago by the De- 

 partment of Agriculture at Washington, and although not use- 

 ful against all forms of insects, is very valuable for household 

 pests, aphides, and small plant-bugs and caterpillars. It is best 

 used dry by dusting the plants affected with an insufflator or 

 bellows while wet with dew. It acts by closing the breathing 

 pores of the insects, and has the advantage of being harmless 

 to man and the higher animals. It is also used in liquid form, 

 as a spray, the buhach being first mixed with enough water to 

 make a thin paste and allowed to stand about two hours, after 

 which more water is added to bring it to the desired strength, 

 the usual proportions being: 2 ounces to 5 gallons of water. 

 An alcoholic decoction is also sometimes used. 



Under different trade names, pyrethrum is placed on the 

 market in hermetically sealed tin cans, so that it retains its full 

 strength until used. Powders that are not packed in tightly 

 sealed cans lose their strength, and are therefore less effective. 

 In small lots pyrethrum costs 10 cents an ounce; if six pounds 

 are purchased it can be had for about 50 cents a pound. 



Tobacco is an old-time remedy for many insects, and still in 

 vogue among a certain class of farmers and florists, but in 

 recent years it has been largely replaced by other and more 

 approved insecticides, such as Paris green and kerosene emul- 

 sion, and in greenhouses by the hydrocyanic-acid gas process. 

 The method of its application varies according to the crop af- 

 fected and the insect. Where tobacco stems and other refuse 

 can be easily obtained from the factories it is advisable to use 

 it as a protection against certain species of insects. 



For the striped cucumber beetle and melon aphis, it is used 

 by sprinkling the hills, particularly when the soil is moist, with 

 refuse dust. Thus used it has the advantage of acting as a 

 fertilizer and mulch for the plant, as well as being a repellent 

 to the beetle and other insects. Applications must be repeated 

 after rainfall. 



