[Objectives]  To clarify the toxicological effect of sublethal doses of avermectin on Hyphantria cunea, and thereby provide a theoretical basis for the rational use of this pesticide. [Methods]  The growth and development of 4^th to 6^th instar H. cunea larvae were measured after these had consumed artificial diets containing sublethal concentrations of abamectin (LC₁₀ or LC₃₀) for 72 h. Control groups were fed an aqueous solution containing 0.1% dimethyl sulfoxide. The reproductive ability of adults obtained from these treatment groups was also measured. [Results] The 4th instar LC₃₀ treatment group grew 22% less than the respective control group (P<0.05), whereas there were no significant differences in growth between the 5th and 6th instar LC₃₀ treatment groups and their respective control groups (P>0.05). There was no significant difference in growth between the LC₁₀ treatment groups and their respective control groups (P>0.05). Development of the 4th, 5th and 6th larval instars in the LC₃₀ treatment groups (3.4, 2.2 and 1.7 days, respectively) was significantly prolonged relative to the respective control groups (P<0.05), but there was no significant difference in the duration of development of the LC₁₀ treatment groups (P>0.05) and the respective control groups. Adult longevity in the LC₁₀ and LC₃₀ treatment groups (1-1.7 and 2.3-2.7 days, respectively) was significantly shorter than that of the respective control groups (P<0.05). The pupation rate, emergence rate, fecundity and hatching rate of the LC₁₀ and LC₃₀ treatment groups were also significantly shorter compared to the respective control groups (P<0.05). Pupation and emergence rates, fecundity, and hatching rate in the LC₃₀ treatment group were 36%-56%, 33%-66%, 49%-78% and 45%-62%, respectively, those of the respective control groups. The fecundity and hatching rate of the LC₁₀ treatment groups were 66-88% and 62-82%, respectively, those of the respective control groups. Only the feeding, larvae period, emergence rates and pupation rates of 4th instar larvae, the larvae period and emergence rates of 5th instar larvae, and the emergence rates and egg hatching rate of 6th instar larvae, were significantly less in the LC₁₀ and LC₃₀ treatment groups than in the respective control groups; the differences were greater for the LC₃₀ treatment group than for the LC₁₀ treatment group. [Conclusion] Exposure of H. cunea larvae to sublethal concentrations of abamectin (LC₁₀ and LC₃₀) inhibits both larval growth and development and the reproductive capacity of larvae that survive to adulthood.