120 HOUSEHOLD INSECTS 



Sulfur candles for fumigating are now made and are 

 very convenient. They may be burned by setting them 

 on bricks in a tub of water or in pans of wood or coal ashes. 



Where swifts have taken possession of a chimney and 

 bugs from them have overrun adjacent rooms it would be 

 advisable to exclude the birds from their roosting place. 

 This could be done by securely fastening heavy wire net- 

 ting over the chimney opening. It would also probably be 

 feasible to fumigate the chimney by burning sulfur in it 

 after closing the top opening tightly. 



Hydrocyanic acid gas. — This is the killing agent, par 

 excellence, for bedbugs and household insects. It is a 

 gas formed by the chemical reaction between potassium 

 cyanide, water, and sulfuric acid, and is a deadly poison 

 to human beings as well as to other animals. However, 

 it can be generated and used in the fumigation of houses, 

 without the least danger, if care .and precaution are 

 used in the work. The gas is not inflammable, does 

 not bleach colors, does not injure fabrics in any way, and 

 does not, in general, attack metals, although it will tarnish 

 nickel fixtures. These should be covered with towels or 

 similar articles. Dry food products are not affected, but 

 milk and butter may absorb some of the gas and should 

 be covered. See Chapter XVII for a discussion of the 

 use of this gas. 



Desiring to know the effect of hydrocyanic acid gas on 

 bugs hidden away in mattresses, blankets, comfortables, 

 and the like, the following experiments were tried : — 



1. Three bugs were placed in a perforated pill box and 

 then wrapped in excelsior, three inches all around, and this 

 in turn in some domestic to imitate ticking. 



2. Three bugs (one adult, one one-third grown, and one 



