The purpose of this study was to evaluate the effect of pesticides on insect pest control of Rhophalosiphum nymphaeae, growth characteristies and dry root yield from the cultivated after early maturing rice cropping. All pesticides treated had no effect on the growh period, flowering rate of Alisma plantago. The major pesticides were methomyl-Lf, 24.1 %, imidacloprid-Wp, 10%, carbosulfan-Wp, 20%, and methomyl-Wp, 45%. Dry yield of root were increased largely with imidacloprid-Wp, 10% (10g/20$ell$), pesticide than the other pesticides and control. All pesticides were had no injury with recommended concentration. On the other hand all pesticides were slightly harmful in the double dosage level for the Alisma plantago.