Abstract
Damage by the rice leaf beetle, a rice insect pest, was studied from 1975 to 1977 in Akita, in northern Japan. When the percentage of leaves injured by the larvae of the rice leaf beetle exceeds 30%, yield loss of rice occurred in some experimental paddy fields. But in other experimental paddy fields, an injury rate exceeding 30% did not cause yield loss of rice. The injury by the larvae tended to cause yield loss in fields in which the increase in the number of tillers was slow or the percentage of productive tillers was small. The yield loss of rice plants injured by the larvae resulted from reduction of the number of ears per hill.
