One of the most significant insect pests of maize in the Philippines is the maize planthopper – scientifically known as Peregrinus maidis Ashmead (Hemiptera: Delphacidae) – which can inflict direct damage and spread the two main viral diseases to corn, the Maize mosaic virus, and Maize stripe virus. This study assessed the efficacy of three insecticides against P. maidis – namely azadirachtin, deltamethrin, and triflumezopyrim. Three different solutions were prepared and used, including the recommended rate. The evaluation focused on sublethal effects and mortality at 6, 12, 24, and 36 h intervals. The mortality rate of the P. maidis was significantly affected by the three insecticides, with p-values ranging from 0.000–0.008, indicating it is against the null hypothesis (p < 0.05). Only the 12-h data fit well, according to probit analysis, with a Pearson correlation of more than 0.80 (0.863–0.994). The findings showed that the LC50 values for azadirachtin, deltamethrin, and triflumezopyrim were 121.89, 12.05, and 8.84 mg/L. respectively. In terms of the treated group's sublethal effects, there was no statistically significant difference between treatments (p > 0.05). Thus, the assessed pesticides' effectiveness in controlling the P. maidis population and preventing its reproduction is notable.