We report the effects of some bisorbicillinoidsisolated from biomass of the fungus Trichoderma citrinovirideon settling and feeding preference of the aphidSchizaphis graminum. Purification of the fungal metaboliteswas carried out by a combination of columnchromatography and thin-layer chromatography usingdirect and reverse phases. Chemical identification wasperformed by spectroscopic methods including nuclearmagnetic resonance and mass spectrometry. The identifiedbisorbicillinoids appeared to be bislongiquinolide, its16,17-dihydro derivative, trichodimerol, and dihydrotrichodimerol.A feeding preference test with alate morphs of S. graminum was used to identify the active fractions. Among the four bisorbicillinoids, dihydrotrichodimerol and bislongiquinolide influenced aphid feeding preference, restraining specimens from settling on leaves treated with metabolites.Taste neurons sensitive to these compounds, particularly tobislongiquinolide, were located on tarsi of the S. graminumalate morphs.