. Report of the State Entomologist of Connecticut for the year ... . s relatively low, asnoted by Weigel (1944), Harness (1944), Nelson (1944) and others. Re-lated materials, however, were reported by manufacturers as having muchhigher toxicity for this insect. Accordingly DDT, Rhothane (dichloro-di-phenyl dichloroethane), and dimethoxy diphenyl trichloroethane (methoxyDDT) were applied to beans for control of larvae of the Mexican bean a standard of comparison, pure ground cube root, as a source of ro-tenone, was used. In addition, hydroxy pentamethyl flavan was tested. Alldusts wer
. Report of the State Entomologist of Connecticut for the year ... . s relatively low, asnoted by Weigel (1944), Harness (1944), Nelson (1944) and others. Re-lated materials, however, were reported by manufacturers as having muchhigher toxicity for this insect. Accordingly DDT, Rhothane (dichloro-di-phenyl dichloroethane), and dimethoxy diphenyl trichloroethane (methoxyDDT) were applied to beans for control of larvae of the Mexican bean a standard of comparison, pure ground cube root, as a source of ro-tenone, was used. In addition, hydroxy pentamethyl flavan was tested. Alldusts were mixed with pyrophyllite diluent except DDT, which was used asmixed at the factory. Dusts were applied on August 15 and 23, 1945, to 10row plots, in three randomized blocks. Applications were made using a smallplunger duster. Results were determined August 29 by taking 10 plants atrandom from each plot and counting the surviving larvae. The results havebeen summarized in Table 26, and dosage response curves for the more ef-fective materials are given in Figure .125 .25 CONCENTRATION .5 - %- LOG SCALE Figure 7. Dosage response curves for organic insecticides to control the Mexican beanbeetle. A. rotenone dust from pure ground cube root. B. dimethoxy diphenyl dichloro diphenyl trichloroethane. D. hydroxy pentamethyl flavan. E. dichloro diphenyldichloroethane. 68 Table 26. Control of Mexican Bean Beetle with Organic Insecticides ., t . Cone. Per cent Matenal per cent No. larvae reduction Cube .1251 99 .25 21 .5 20 1 DDT .5 101 187 36 78 Methoxy DDT .5 12 7 4 2 Rhothane .5 238 300 214 216 Hydroxy pentamethyl 260 flavan 64 25 4 No treatment 327 1 rotenone As was expected, DDT was much less effective than rotenone in of the concentrations used killed as many larvae as .25 per cent ro-teno
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