An insecticide application to termites is obtained comprising at least one member selected from a plant, an extract of the plant, and an ooze (or exudate) of the plant, wherein the plant belongs to at least one genus selected from the group consisting of the genus Geranium, the genus Morus, the genus Artemisia, the genus Diospyros, the genus Crataegus, the genus Curcuma, the genus Rubia, the genus Polygonum, the genus Gardenia, the genus Cornus, the genus Uncaria, the genus Rheum, the genus Terminalia and the genus Saussurea. The extract may be a substance extracted with at least one member selected from the group consisting of water and a hydrophilic solvent. The insecticide exhibits high insecticidal and insect-controlling activity against insects (e.g., sanitarily injurious insects, insects injurious to houses and particularly to timber such as termites), being highly safe to human beings and animals and not adversely affecting the environment.