INSECTICIDES AND REPELLENTS 



67 



DDT has been used with great success in crowded, low-rental 

 sleeping quarters in the poorer sections of large cities. It is from 

 such places that reports of DDT resistance in bed bugs have been 

 received. 



If DDT fails to control bed bugs, a synergized pyrethrum spray 

 is recommended. The spray should contain 0.2 percent of pyrethrins 

 and 1 percent of piperonyl butoxide, and should be used as a residual 

 treatment as described for DDT. This spray is less persistent than 

 DDT and a second treatment is suggested within 2 to 4 weeks. Sprays 

 and dusts containing 1 percent of lindane have been employed 

 effectively by commercial operators. 



COCKROACHES 



Chlordane is more toxic than DDT to cockroaches and is recom- 

 mended for their control. It is usually applied in a 2-percent kero- 

 sene solution or emulsion with a pressure sprayer or power equip- 

 ment, but a 5-percent dust may be used. In living quarters applica- 

 tion should be limited to places where the roaches commonly crawl 

 or hide, such as baseboards, corners, large cracks, pantry shelves, 

 and behind furniture and kitchen sinks (fig. 28). As is true for all 

 indoor spraying, special care must be taken to protect food and dishes 

 from contamination. In pantries, cupboards, and the underside 





Figure 28. — Dusting for control of cockroache: 



