Methanol extracts from 28 samples of 22 plant species in 17 different plant families were tested at 10,000 ppm for evaluating their insecticidal and acaricidal activities against Tetranychus urticae Koch, Aphis gossypii Glover, Myzus persicae Sulzer, Trialeurodes vaporariorum (Westwood), and Panonychus citri (McGregor). In a test with T. urticae, extracts from Albizzia coreana twig and Pyracantha angustifolia leaf possessed potent acaricidal activities. Reproduction of T. urticae for three days significantly decreased in the extract treatments of Gardenia jasminoides, Ficus carica, and Albizzia coreana twigs. Though slight repellent activities against T. urticae were obtained from extracts of Camellia japonica seed, G. jasminoides peel and fruits, Ligustrum japonicum leaves, A. coreana twig, and Machilus thunbergii leaves in 24 h after treatment, but tended to decrease in 72 h. Extracts of F. carica leaves and G. jasminoides fruits had potent insecticidal activities against M. persicae and A. gossypii. Methanol extracts of F. carica leaves possessed insecticidal activity against T. vaporariorum. In a field test with P. citri, extracts from C. japonica seeds, A. coreana leaves, Ranunculus japonicus leaves and roots, an Houttuynia cordata leaves exhibited acaricidal activities.