Abstract
Two new methods for screening repellents for cockroaches are described. The slanting card method is based on the tendency of cockroaches to climb a slanting surface. Cards impregnated with test chemicals are placed in a slanting position against the inside walls of a transparent plastic box containing a colony of cockroaches. The number of insects on the treated cards is compared with the number on an untreated card. The ground glass cylinder method employs three intercommunicating glass cylinders ground on the inside to keep the cockroaches on treated filter papers or other surfaces at the bottom. By this method the best repellents from more than 1000 chemicals tested were 2,3,4,5-bis(∆2-butenylene)tetrahydrofurfural (R-11), 2-hydroxy-ethyl n-octyl sulfide (R-874), 2-hydroxypropyl n-octyl sulfide (R-949) and tert-butylsulfenyl dimethyl dithiocarbamate (R-55). (N (2-Ethylhexyl) bicyclo-2,2,1-hept-5-ene-2,3-dicarboxa-mide (MGK-264) is synergistic with R-11. Although highly effective, R-55 is more toxic and has more odor than R-11 or R-874. R-874 appears superior to R-11 as a cockroach repellent.
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