Insecticidal activities and effects on three enzymic activities caused by 5-aminolevulinic acid (ALA) on Oxya chinensiswere studied. Fourth-instar nymphs of O. chinensis were treated with different doses of ALA (A1, 250 mM; A2, 450 mM;A3, 750 mM; A4, 1 000 mM). Mortality and the activities of acetylcholinesterase (AChE), glutathione S-transferase (GSTs),and glutathione peroxidase (GPx) were determinated. The mortality of O. chinensis rose with an increasing dose of ALA.The mortality of high-dose treatments A3 and A4 reached 66.19 and 80.21%, respectively. The value of LD50 was3.61 (3.29-3.93) mg g-1 body weight (95% confidence interval). Biochemical studies showed that the activities of AChE andGPx in the A4 treatment declined by 51.53 and 42.82% in the female, and 42.65 and 43.85% in the male compared to thecontrol, respectively, and the degree of decline reached a significant level at P < 0.05. Meanwhile, the GSTs activitiesof O. chinensis enhanced with increasing dose of ALA. The GSTs activities of female and male O. chinensis in the A4treatment remarkably increased by 171.05 and 97.42% compared to the control (P < 0.05). ALA had an obviously toxiceffect on O. chinensis. Moreover, ALA caused the photoinactivation of AChE and GPx, which induced nerve transmissionblocking and the capability to defend oxidation damage declining. Meanwhile, a high dose of ALA could activate GSTs,which caused a feedback inhibition of the insect to the phototoxic substance. Insecticidal activities and effects on three enzymic activities caused by 5-aminolevulinic acid (ALA) on Oxya chinensiswere studied. Fourth-instar nymphs of O. chinensis were treated with different doses of ALA (A1, 250 mM; A2, 450 mM; 750 mg; A4, 1000 mM). Mortality and the activities of acetylcholinesterase (AChE), glutathione S-transferase (GSTs), and glutathione peroxidase (GPx) were determinated. The mortality of O. chinensis rose with an increasing dose of ALA The mortality of high-dose treatments A3 and A4 reached 66.19 and 80.21%, respectively. The value of LD50 was 3.61 (3.29-3.93) mg g-1 body weight (95% confidence interval). Biochemical studies showed that the activities of AChE and GPx in the A4 treatment declined by 51.53 and 42.82% in the female, and 42.65 and 43.85% in the male compared to the control, respectively, and the degree of decline reached a significant level at P <0.05. Meanwhile, the GSTs activities of O. chinensis enhanced with increasing dose of ALA. The GS Ts activities of female and male O. chinensis in the A4treatment remarkably increased by 171.05 and 97.42% compared to the control (P <0.05). ALA had an obviously toxiceffect on O. chinensis. Moreover, ALA caused the photoinactivation of AChE and GPx, which induced nerve transmissionblocking and the capability to defend oxidation damage declining. Meanwhile, a high dose of ALA could activate GSTs, which caused a feedback inhibition of the insect to the phototoxic substance.