Eucalyptus cultivation has undergone great expansion in recent years due to the increase in commercial production of this wood for the paper, cellulose and steel industries. One of the main factors responsible for production losses is insect attack. The main insect that acts as a pest, devastating eucalyptus plantations is Thaumastocoris peregrinus, being controlled through the application of synthetic insecticides. The objective was to evaluate the potential of the aqueous extract of neem leaves for the alternative control of T. peregrinus. The survival of T. peregrinus was evaluated in two experiments with higher (20, 40, 60 and 80%) and lower (1, 5, 10 and 20%) concentrations of aqueous extract of neem leaf. The experiment took place under laboratory conditions at a controlled temperature of 25 ± 2°C. In the first experiment, higher concentrations were more effective in reducing survival. In the second experiment, the lowest concentrations reduced less effectively. It is concluded that the aqueous extract of neem leaves in higher concentrations has an insecticidal effect against T. peregrinus, reducing the survival of adults of this species.