The author carried out a study on the effectiveness of the boric acid as a stomach poison for German cockroach control from July to September 1971. The test was performed by the feeding method under conditions of 20 C and 80 per cent relative humidity. The baits were composed of one control group and five different combination groups with boric acid and sugar as follows. 10 g sugar only(control group), 1 g powedered boric acid to 9 g sugar(1:9 poison baits), 2 g powdered boric acid to 8 g sugar(2:8 poison baits), 4 g powdered boric acid to 6 g sugar(4:6 poison baits), 5 g powdered boric acid to 5g sugar(5:5 poison baits), 10 g powdered boric acid only (10:0 poison baits). The insects were composed of 360 female adult German cockroaches collected by traps at the kitchens of restaurants and house holds in Seoul City. The results were as follows: The total mortality by poison baits in 72 hours after treatment were: 44.3 per cent by 1:9 poison baits , 79.4 per cent by 2: poison baits , 96.7 per cent by 4:6 poison baits(the most effective poison baits), 88.3 per cent by 5:5 poison baits, 91.1 per cent by 10:0 poison baits. The peak mortality by the treatment hours were: Up to 21 hours: 23.3 per cent by 5:5 poison baits, 20.0 per cent by 10:10 poison baits, From 24 to 48 hours: 71.1 per cent by 4:6 poison baits, 55.6 per cent by 10:0 poison baits, From 48 to 72 hours: 21.9 per cent by 2:8 poison baits, 19.6 per cent by 1:9 poison baits. The most effective treatment hours was from 24 to 48 hours.
parasitology-arthropoda-cockcroach ; Blattella germanica ; chemotherapy ; boric acid

During the period from May to October 1969, the authors carried out a series of tests with the aim to ascertain the present status of susceptibility of adult cockraoches to various insecticides. The tests on the susceptibility of cockroaches to dieldrin, D.D.V.P., Diazinon; Dibrom, Malathion and lindane were performed with the topical application and the residual film methods under the conditions of 26 degrees C and 80% of relative humidity. The insects tested were collected from Seoul City and were reared at the laboratory. Some of the important results so far obtained can be summarized as follows: The median lethal doses (LD(50)) of the five insecticides against female adult cockroaches were: 0.4 ug/roach or 4.02 ug/body weight (gm) by Dieldrin, 0.29/roach or 2.88 ug/body weight (gm) by D.D.V.P., 0.29 ug/roach or 2.96 ug/body weight (gm) by Diazinon, 0.54 ug/roach or 5.37 ug/body weight (gm) by Dibrom, and 2.96 ug/roach or 29.60 ug/body weight (gm) by Malathion. And those against male adult cockroaches were: 0.18 ug/roach or 3.29 ug/body weight (gm) by Dieldrin, 0.27 ug/roach or 4.89 ug/body weight (gm) by D.D.V.P., 0.16 ug/roach or 2.91 ug/body weight (gm) by Diazinon, 0.49 ug/roach or 8.97 ug/body weight (gm) by Dibrom, and 1.32 ug/roach or 24.19 ug/body weight (gm) by Malathion. The level of susceptibility of adult cockroaches to the insecticides tested was 1.0-1.6 times higher as compared with the results obtained on the Japanese Takashi strain. The median knockdown times (LT(50)) of the female adult cockroaches by insectcides at 1% concentration of 3 mg per square centimetre were 1.82 hours by Malathion, 1.36 hours by Diazinon, 0.56 hours by Lindane, 0.50 hours by Dibrom, and 2.56 hours by D.D.V.P. A marked difference was seen to exist between the males and the females. The female cockroaches were more resistant than the male to Dieldrin, Diazinon and Malathion.
parasitology-arthropoda-cockcroach-Blattella germanica ; chemotherapy ; Dieldrin ; D.D.V.P. ; Diazinon ; Dibrom ; Malathion ; lindane ; resistance