Biological tests with Thymus vulgaris against both third and fifth instar larvae of Thaumetopoea pityocampa showed positive correlation between the used doses and mortality after 24 h of application. Treatment against third instars larvae with doses 0.005–0.04 ml L⁻¹ gave 40.97–100% mortalities in vitro condition, and treatment with doses 0.1–0.5 ml L⁻¹ gave 53.85 and 100% mortalities in vivo condition. In addition, similar effect of this natural insecticide is observed against fifth instars larvae with mortality rate varying between 36.11 and 100% at doses of 0.02–0.1 ml in vitro and between 33.96 and 100% mortality with doses of 0.3–1.2 ml in vivo. Bioassay with Lavandula angustifolia against third instar larvae in vitro condition showed between 29.86 and 100% mortality rate, but with high doses between 0.01 and 0.05 ml L⁻¹ compared to T. vulgaris. Furthermore, the mortality recorded in vivo is 73.35% with dose of 1 ml L⁻¹. Whereas the essential oil of L. angustifolia is the least toxic against fifth instar larvae of Thaumetopoea pityocampa with 37.08% at a dose of 1.5 ml L⁻¹ in vivo and 65.97% mortality at a dose of 0.12 ml L⁻¹ in vitro. Histologically, the effect of these essential oils has resulted in a necrosis and degeneration of the intestinal cells, as well as a general destruction of the hair and skin of treated larvae compared to untreated caterpillars. In accordance with these results, it would be possible to use essential oil of T. vulgaris as an effective biological alternative against the larvae of T. pityocampa. The chemical analyses obtained by GC–MS of T. vulgaris essential oil enabled us to identify 35 chemical compounds of which Carvacrol (71%) is the most dominant, whereas for L. angustifolia there are 36 chemical compounds of which we have identified two dominant chemical compounds, Lynalol (37%) and Linalool acetate (25%).

用寻常的百里香对拟南芥的第三和第五龄幼虫进行的生物学测试表明，施用剂量与24小时后的使用剂量和死亡率呈正相关。剂量为0.005-0.04 ml L ^-1的三龄幼虫的体外治疗死亡率为40.97-100％，而剂量为0.1-0.5 ml L ^-1的第三龄幼虫的体内死亡率为53.85和100％。此外，这种天然杀虫剂对五龄幼虫的杀灭作用相似，在体外剂量为0.02–0.1 ml时死亡率为36.11至100％，在体内剂量为0.3–1.2 ml时死亡率为33.96至100％。薰衣草的生物测定对抗三龄幼虫的体外死亡率显示为29.86至100％的死亡率，但相对于寻常型T.而言，剂量为0.01至0.05 ml L ^-1。此外，以1ml L ^-1的剂量在体内记录的死亡率为73.35％。而挥发油L.沙枣是针对的第五龄幼虫毒性最小Thaumetopoea pityocampa与37.08％的剂量为1.5ml大号^-1体内和65.97％的死亡率的剂量0.12毫升大号^-1体外。从组织学上讲，与未处理的毛毛虫相比，这些精油的作用导致了肠道细胞的坏死和变性，以及处理后的幼虫的头发和皮肤的普遍破坏。根据这些结果，有可能使用寻常的T. vulgaris精油作为对抗棉铃虫幼虫的有效生物替代品。通过气相色谱-质谱法对寻常型三叶草精油进行的化学分析使我们能够鉴定出35种化合物，其中香芹酚（占71％）是最主要的化合物，而对于安氏杜鹃，则有36种化合物我们已经鉴定出了两种主要化合物化合物，Lynalol（37％）和乙酸芳樟醇（25％）。