1 0 0 0 OA ヒゲナガヤチバエの生活史
The results of our observation on the biology of Sepedon sauteri Hendel are as follows. The adult is found along the paddy-field, ditch, pond, etc., and lays the egg-mass on the leaves of various plants growing close by the water. The larva, which has difficulty in respiration below the water and floats on the top of the water, attacks Lymnaea (Galba) ollula Gould, which is an intermediate host of the fluke, at the edge of the water. It passes three instars and kills six to sixteen snails until pupation which takes place throughout the waterside. It seems that the reproduction occurs from April to September in which a number of generations comes to pass and the hibernation is made only at the adult stage. The developmental period is shown in Table 1. It is interesting to note that the egg is parasitized by Trichogramma japonium Ash-mead which is a natural enemy of the rice stem borer, Chilo suppressalis Walker.