The investigations on host selection of phytophagous insects revealed that acceptance or rejection of a plant species is governed by the presence or absence of attractants or repellents in plants. Naturally occurring substances derived from plants which exhibit feeding inhibitory activities to biting insects or piercing insects have been found cumulatively. The authors surveyed the presence of insect feeding inhibitors in various plant extracts and botanical products against the larvae of Spodoptera litura known as a polyphagous pest insect. This report deals with the examination for insect feeding inhibitors in plant extracts and the isolation and identification of six feeding inhibitors from Orixa japonica (Kokusagi in Japanese). Isopimpinellin, bergapten, xanthotoxin, kokusagine, evoxine and japonin were isolated and identified in the leaves of Orixa japonica (Rutaceae) as feeding inhibitors against Spodoptera litura F. (Noctuidae). Isopimpinellin exhibited the most potent activity among above substances at the feeding inhibitory test. The isolated evoxine was the optical antipode of the previously reported one.