During recent decades, one of the most important methods of replacing synthetic pesticides is using of new formulations based on plant essential oils (EOs) that can improve their quality and effectiveness. Due to restrictions in application of EOs in pure form, preparation of their commercial formulations is essential. In this research, the contact toxicity of fifteen different plant EOs on 1st instar nymphs of Phenacoccus solenopsis was examined at 25± 1° C, 65± 5% RH, and a photoperiod of 16: 8 h = L: D. Three EOs including; Mentha longifolia (L. ), Mentha piperita (L. ), and Oliveria decumbens (Vent. ) had the highest contact toxicity and were considered for the next experiments. According to GC and GC/MS analysis, pulegone (51. 49%), menthone (22. 75%), and 1, 8-cineole (11. 69%) were the principal components of M. longifolia; menthone (36. 51%), menthene (28. 51%), menthol (8. 12%), and 1, 8-cineole (7. 66%) were the principal components of M. piperita and the main components of O. decumbens EO were thymol (43. 99%), γ-terpinene (13. 96%), and p-cymene (12. 62%). Moreover, contact toxicity of the EOs were evaluated on 1st instar nymphs of P. solenopsis under laboratory conditions, before and after formulation. Based on lethal concentration trials, LC50 values of pure and formulated EOs of M. longifolia, M. piperita, and O. decumbens on 1st instar nymphs were 113. 49, 129. 74, 149. 93, and 48. 22, 55. 55, 61. 68 ppm, respectively; after 48 hours. Therefore, the contact toxicity of formulated EOs of M. longifolia, M. piperita, and O. decumbens were 2. 34, 2. 36, and 2. 43-fold higher than the pure EOs. Based on physicochemical trials, the prepared formulations were stable under the experimental conditions. Therefore, formulation of EOs of examined plants can be considered as new environmentally friend pesticides for controlling of the pests.