The stomach contents of the Japanese tree frog, Hyla japonica, captured in soybean fields, were analyzed to examine whether this frog species is a beneficial natural enemy. From 101 frog stomachs, 1,545 prey items were identified. The diet consisted of a wide variety of arthropods. Aphids predominated in the diet, making up 67.2% of total prey. Leaf beetles and catarpillars were also found frequently in stomach contents. These insects are probably pest species, although most prey items were not identified at the level of species; therefore, H. japonica could be considered a beneficial natural enemy of various soybean pest species. In order to increase the density of H. japonica and enhance the effect of pest control by predation, soybean fields should be placed near rice fields where H. japonica spawns, to attract the frog after spawning and metamorphosis.
