The study was conducted to investigate the botanical pesticides or phytopesticides used by the ethnic farmers to control insect pests in the Dimapur district of Nagaland and their phytochemical analysis. This study broadly aimed to contribute to modern biopesticide formulation. Thirty-five locally grown phytopesticidal species belonging to 31 genera and 21 families were recorded. Asteraceae and Zingiberaceae possessed the highest number of species with 4 each followed by Solanaceae and Lamiaceae (3 species each). Among the species, 14 herbs, 10 trees, 9 shrubs, 1 climber and 1 creeper were present. Twenty types of insect pests including termites stem borers, nematodes, jassids, aphids, grasshoppers, semiloopers, whiteflies, cutworms, armyworms, gundhi bugs, ants, caterpillars, thrips, leaf miners, leaf webbers, beetles, etc., were reported. Eight different plant parts were used as phytopesticides. The highest used plant part was the leaf with 80% use reports. The lowest used part was the stem (2.85%). Twelve modes of traditional pesticide formulation were recorded from the study. Quantitative indices like use value (UV) and family use value (FUV) of the botanical pesticides were calculated. Azadirachta indica has shown the highest use value. The lowest use value was 0.06, recorded for Tamarindus indica and Cucumis sativus. Similarly, Caricaceae showed Cucurbitaceae and Fabaceae showed the highest FUV of 0.52, and the lowest FUV with the FUV of 0.06 each. Out of 35 species, 32 species possessed alkaloids; flavonoids and tannins were present in 30 species each, saponins were present in 28 species, terpenoids were found in 21 species, and glycosides were detected in 20 species. Five different botanical pesticide preparation methods were recorded. Shortly, such plants would contribute to formulating modern biopesticides with better outcomes.