Abstract
Notiphila sekiyai KOIZUMI (Ephydridae) was first found in Hokuriku district of Japan in 1948 attacking the root of rice plants in te paddy field. In the present paper, the authors dealt with some morphological and ecological investigations of this insect for the purpose of its control. The results obtained are summarized as follows : 1. The eggs are laid on the leaf sheath of the rice plant as an egg-mass containing 1 to 5 eggs. An egg has dry-mud like surface, and its length is about 1.2 mm and width about 0.3 mm. Larva is yellowish milky white, its length is 7 to 8mm in its last stage and terminal segment is long and slender, about 1/5 of body length. Pupa is red brown with club like shape, and the tail part is as long as the larva. 2. Today, this insect is found to be distributed in Niigata, Toyama, Ishikawa, Shizuoka and Okayama prefectures, and is recognized to injure the rice plant in all the above districts except in Okayama prefecture. 3. It seems that the said insect has one generation a year and overwinters in the last instar of larvae . 4. The adult fly is active only in the daytime, the copulation and oviposition are observed from about 7 to 10 o'clock. The egg-mass is laid on the leaf sheath of 2 to 6cm above the water surface. Its activity is supressed in high temperature with sun shine. 5. The larva penetrates its posterior spiracle into the root tissue, and eats and cuts off the roots. Such injury continues for 25 to 30 days from the rice transplanting till it pupates. 6. The growth of rice plants injured by the larvae will be supressed and thier leaf colour fades because of the damage to the roots. Consequently, the stems do not increase and the crop yield decreases. 7. Good control results were obtained by the application of dieldrin or aldrin at the dosage of 3g per tubo (about 3.2 m^2) with 20 to 30 per cent of increase in yield as compared with the untreated ones.
