Toxicity of Jojoba and Flax oils against laboratory strains of pink bollworm, Pectinophora gossypiella (Saund.) and spiny bollworm, Earias insulana (Boisd.) newly hatched larvae was tested. Moreover, influence of these oils on some biological parameters was studied. In current investigation, Jojoba oil proved as the most effective compound against the newly hatched larvae of P. gossypiella and E. insulana and LC₅₀ values were 0.9770% and 8.2059% of Jojoba on both pests, respectively. Feeding neonate larvae of both insects on treated artificial diet withLC50 of tested oils led to a complex symptom which proved as higher prolongation for larval and pupa durations than the untreated check (control). Larval duration in P. gossypiella, reached 18.67, 19.67 &14.17 days for Jojoba, flax oil and control, respectively. However, for the pupal duration it reached 11.33, 12.67and 8.8days, in the same respectand this led to marked prolongation in the total immature stages. The resulted showed same performance for E. insulana. Significant reductions in the number of deposited eggs and hatched eggs by each female, which was developed after treating the larvae with the tested oils compared with the control.