Abstract Essential oils can be an important tool for controlling crop pests, but to use it as a complement of biological control is also necessary to determine its toxicity to beneficial insects. The goal of this research was to study the fumigant activity of essential oil (EO) extracted from leaves of Laurelia sempervirens R. et. P. Tul. against adults of Trialeurodes vaporariorum (Westwood) and the parasitoid Encarsia formosa (Gahan) under laboratory conditions. The compounds found in higher percentage in the EO were: safrole (α and β isosafrole) (33.9%), linalool (16.18%), and α-pinene (8.55%). The EO (1–16 μL L−1 air) was very effective against T. vaporariorum (LC50 = 3.77 μL L−1 air), but also very toxic for E. Formosa (LC50 = 0.86 μL L−1 air). The essential oil worked faster at higher concentrations, and when the EO was assayed at concentration from 2 to 16 μL L−1 air, the LT50 values dropped from 4.27 h to 2.61 h for T. vaporariorum, and from 4.04 h to 0.21 h for E. Formosa. The reproduction of E. formosa was significantly affected by the EO when applied at very low doses. The host attack percentage was lower, and the number of descendants per female also decreased. These preliminary results indicate that it would not be possible to use this EO in combination with E. formosa for controlling the greenhouse whitefly T. vaporariorum.