450 HOUSEHOLD INSECTS 



coolly and quickly and holds the breath for a few seconds 

 until the door is reached. The chemical reaction is 

 very rapid and begins immediately, but by reaching 

 the hand out over the bowl and then turning the head a 

 little away and holding the breath a few seconds, we have 

 never in all of our work and we have always done it 

 that way experienced the slightest annoyance from the 

 gas. By passing rapidly down the hall from room to 

 room and floor to floor two men will set the whole 50 rooms 

 off in ten or fifteen minutes. 



Our success was very gratifying indeed, although we had 

 some complaints of bedbugs in a few rooms late in the 

 season. This, in most instances, could be traced to some 

 old wooden bedsteads, that had not been fumigated, and 

 which were to be thrown out and destroyed, but which 

 were used afterwards by students who, coming late in the 

 session and finding these old bedsteads, utilized them 

 instead of buying new ones. In a few cases it was prob- 

 ably due to the large cracks around the doors, through 

 which the gas dissipated itself into the halls. To obviate 

 this difficulty we tried a plan later that seemed to work 

 very well and proved more effective. 



Instead of calking all the rooms in a division we simply 

 calked the rooms on the top floor of that division first 

 and then fumigated them at once. As the operator 

 would close the door of a room, two men, who stood ready 

 with water-soaked strips of paper, would quickly seal the 

 cracks around the edges of the door and the keyhole. 

 These two men would calk a door in less than two minutes 

 and the rooms must have been made as tight as is possible 

 under average conditions. All of the rooms on that floor 

 were treated in this way, after which the force passed to 



