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There are many propi-ietary substances which claim to be fairly 

 effective roach poisons. The usefulness of most of these is, how- 

 ever, very problematical, and disappointment will ordinarily f{;llow 

 their application. The only one of these that has given very satis- 

 factory results is a phosphorous paste, also sold in the form of pills. 

 It consists of sweetened flour paste containing 1 to 2 per cent of 

 phosphorus, and is spread on bits of paper or cardboard and placed 

 in the runways of the roaches. It has been used very successfully 

 in the Department to free desks from Croton bugs, numbers of the 

 dead insects being found in the drawers everj- day during the time 

 the poison was kept about. It is also a repellent. 



Fumigation. — In addition to the hydrocyanic- acid gas treatment 

 noted above, two or three other forms of fumigation may be 

 employed against house roaches. Wherever roaches infest small 

 rooms or apartments which may be sealed up nearly air-tight, and 

 also on shipboard, the roach nuisance can be greatly abated by the 

 proper use of poisonous gases, notably bisulphide of carbon. This 

 substance, distributed about a pantry or room in open vessels, will 

 evaporate, and, if used at the rate of one pound to every 1,000 

 cubic feet of room space, will destroy roaches. Unless the room 

 can be very tightlj^ sealed up, however, the vapor dissipates so 

 rapidly that its effect will be lost before the roaches are killed. The 

 hatches of ships, especially of smaller coasting vessels, niaj^ be bat- 

 tened down, a very liberal application of bisulphide of carbon having 

 been previously made throughout the interior. If left for twenty- 

 four hours the roaches and all other vermin will unquestionably 

 have been destroyed. In the use of this substance it must be always 

 borne in mind that it is violently explosive in the presence of fire, 

 and every possible precaution should be taken to see that no fire is 

 in or about the premises during the treatment. It is also deadly to 

 higher animals, and compartments should be thoroughly aired after 

 fumigation. 



A safer remedy of the same nature consists in burning pyrethrum 

 in the infested apartment. The smoke and vapors generated b}' the 

 burning of this insecticide are often more effective in destroying 

 roaches than the application of the substance in the ordinary way as 

 a powder. There is no attendant danger of explosion, and the only 

 precaution necessar}^ is to see that the room is kept tightly closed for 

 from six to twelve hours. The smoke of burning gunpowder is also 

 very obnoxious and deadly to roaches, particularly the black English 

 roach. On the authority of Mr. Theo. Pergande, gunpowder is 

 commonly used in Germany to drive these roaches out of their 

 haunts about fireplaces. The method consists in molding cones of 

 the moistened powder and placing them in the empty fireplace and 

 lighting them. The smoke coming from the burning powder causes 



