6 BULLETIN 707, U. S, DEPARTMENT OF AGRICULTURE. 



The principal fact of interest in these data is that such violent 

 stomach poisons as arsenious oxid and Paris green were found to be 

 ineffective, as were also the milder sodium fluorid, lead acetate, 

 borax, and boracic acid. These results show conclusively that bed- 

 bugs can be controlled only by an insecticide which acts directly on 

 the body, and that none of the materials with which the insect comes 

 in contact is taken into the stomach. 



Although, in a few cases, these materials appeared to have some 

 slight effect on the insects, the number killed was so small that they 

 would be of no value under practical conditions. 



PHOSPHORUS PASTES. 



Two tests were made with pastes formed of sugar, water, and 

 starchy material, and containing, in one case, 1.91 per cent and, in 

 the other, 2.21 per cent of phosphorus. The first test was made in 

 a room badly infested with bedbugs, and the paste was liberally 

 smeared in the corners of the bedstead and in the cracks around the 

 baseboards and moldings. Observations were made several days 

 after treatment, and it was then evident that this material was of no 

 value. Hundreds of living bugs were present, and the only dead 

 ones seen were a very few that had become entangled in the paste and 

 stuck fast. 



In the second test the paste was smeared on pieces of paper and 

 placed in a box containing 50 bedbugs. One week later examination 

 showed that 90 per cent of the insects were still living and active. 



FUMIGATION AGAINST BEDBUGS. 



Eesults obtained in a limited number of tests made with sulphur 

 as a fumigant show that it will kill bedbugs, and indicate that 

 the necessary amount for effective use is at least 1 pound to 1,000 

 cubic feet of room space. 



Not only is sulphur fumigation effective against the bedbugs 

 themselves, but it has been found by several workers to kill the eggs 

 also, which makes it a very satisfactory method of fighting this in- 

 sect. This effectiveness against the eggs is of particular importance, 

 since they are often deposited in inaccessible cracks and holes, or 

 behind wall paper, where it is very difficult, or even impossible, to 

 reach them with a dust or spray. 



The following materials were found to be ineffective as fumigants 

 against bedbugs when used at the rate indicated : 



Paradichlorobenzene (8.5 pounds to 1,000 cubic feet). 

 Paraformaldehyde (2.25 pounds to 1,000 cubic feet). 

 Charcoal (1.64 pounds to 1,000 cubic feet). 



