56 APPLIED ENTOMOLOGY 



practice is to put the liquid in rather flat dishes close to the top of the 

 place to be fumigated, as the gas will develop more rapidly in such dishes 

 and work downward from its source. All openings into this place must 

 then be tightly closed at once and everything be left undisturbed for from 

 24 to 48 hr. Ventilate well from outside before entering. 



The chief disadvantage in the use of this gas is that it is quite inflam- 

 mable and cannot be used near where there is a fire or highly heated pipes 

 of any kind. In such quantities as the operator is likely to inhale while 

 using it, a headache is generally the most serious result, though persons 

 with heart trouble of any kind should not work with it as it has some effect 

 on that organ. 



Carbon disulfid is used chiefly against clothes moths, carpet beetles, 

 stored grain pests, pea, bean, and other seed pests, ants, and borers in 

 trees. It cannot safely be used in greenhouses or with plants. Details 

 of its uses in different cases will be given in connection with the different 

 insects concerned. 



Nicotine. Nicotine as a vapor may be obtained by evaporating the 

 decoction of it mentioned in the last chapter, in a dish over a lamp, but 

 the uncertainty as to its strength makes treatment in this way liable to 

 prove unsatisfactory. 



Nicotine 40 per cent, both in liquid form and as paper rolls saturated 

 with it, are on the market and supply a material of known strength with 

 which to work. It is of value as a treatment for plant lice and other 

 delicate insects. A fluid ounce added to a little water, and this evapo- 

 rated by heat will be sufficient for about l,000cu. ft. of space, provided the 

 place is quite tight; or four or five sheets of the paper are usually enough. 

 Upon lighting, the paper smolders, giving off the nicotine vapor. The 

 length of time necessary for nicotine treatment varies with different 

 insects, but is generally begun in the evening, continued all night, and 

 the place opened and aired the next morning. 



Sulfur. The value of sulfur as a fumigant is probably due both to its 

 combination on burning with the oxygen of the air, eliminating this and 

 suffocating the insect, and to the formation in this way of a poisonous gas. 

 It is prepared by burning powdered sulfur in the place to be fumigated, 

 and is used for household pests and also in greenhouses between crops. 

 It cannot be safely used with living plants. From 1 to 2 Ib. of sulfur per 

 1,000 cu. ft. of space is the usual quantity used. Polished metal surfaces 

 in the place to be fumigated will become tarnished by the gas, and these 

 should be removed, as well as colored goods which are bleached by it. 

 Metal can be protected by covering it with vaseline. 



The general practice is to place a large iron kettle on bricks to keep 

 it off the floor, which in that place should be covered for a distance of 

 several feet with something which will not be injured or burned if the 

 sulfur spatters over. In the kettle place the sulfur and add to it a little 



