Physico-chemical properties of crude diesel oil and botanical synthetic materials (thymol and camphor) were studied and prepared as emulsifiable concentrate formulation (EC). Prepared formulations passed successfully specified testes, then their toxicity were investigated against different stages of mealybug Ferrisia virgata (Cockerell) under laboratory conditions. Results indicated that all tested formulations showed high toxicity against all tested insect stages. The mixing, thymol or camphor with diesel oil increased toxicity of oil against mealybug F. virgate, whereas mixture, thymol with diesel oil was more effective than camphor with diesel oil. LC₅₀ values after two days of application were 4.02, 4.51, 4.86 and 5.33 ml/l for diesel oil, while it were 0.17, 0.17, 0.25, and 0.25ml/l for mixture of oil and thymol, and 0.88, 0.99, 1.12, and 1.24 ml/l for mixture of diesel oil and camphor for first, second, third and adult stages of F. virgate respectively. While LC₅₀ values after three days of application were: 1.43, 1.49, 1.61 and 1.77 ml/l for diesel oil, while it were 0.03, 0.03, 0.08 and 0.11 ml/l for mixture of oil with thymol, and 0.14, 0.24, 0.21 and 0.16 ml/l for mixture of oil with camphor for 1^st, 2^nd, 3^rd and adult of F. virgate respectively. Results showed, efficacy of tested materials increased by increasing concentration and period after application and mixing botanical synthetic materials with diesel oil increased toxicity against all tested stages; moreover, mixtures could be used for controlling mealybug in medical, aromatic and ornamental plants after conducting more semi-field and field experiments.