34 THE ORTHOPTERA OF MINNESOTA. 



tight, and also on shipboard, the roach nuisance 

 can be greatly abated by the proper use of 

 poisonous gases, notabl}- bisulphide of carbon. This 

 substance, distributed about a pantry or room in open 

 vessels, will evaporate, and, if used in sufficient quantity, 

 will destroy roaches. Unless the room can be very tightl}'- 

 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, may be bat- 

 tened down, a very liberal application of bisulphide of car- 

 bon having been previously made throughout the interior. 

 If left for twenty-four hours the roaches and all other ver- 

 min 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 thoroughK^ 

 aired after fumigation. A safer remedy of the same nature 

 consists in burning pyrethrum in the infested apartment. 

 The smoke and vapors generated by the burning of this in- 

 secticide 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 necessary 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 deadW to 

 roaches, particularly the black English roach. On the au- 

 thority 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 fire- 

 place and lighting them. The smoke coming from the burn- 

 ing powder causes the roaches to come out of the crevices 

 about the chimney and fire bricks in great numbers, and 

 rapidly paralyzes or kills them, so that they may be after- 



