Technical Abstract: Enhancing biological control in orchards is an efficient way to control insect pests when effective. This study investigates the possibility of increasing biological control of spirea aphid by providing alternate food resources, in the form of peach extrafloral nectar, to adult Harmonia axyridis, the most important predator. Two pairs of apple orchards, each with one interplanted with 50% trees bearing extrafloral nectar and one a monoculture, were studied for aphid and predator populations from 1999 to 2005. There were no differences in spirea aphid populations between interplanted and monoculture orchards. However, H. axyridis adults arrived earlier in the interplanted than in the monoculture orchards. In another apple orchard, the effect of peach extrafloral nectar was tested comparing biological control on sentinel spirea aphid colonies on apple trees surrounding a cluster of potted peach trees, or a cluster of apple trees as a control. Only the closest spirea colonies to the potted peach trees, on trees within 3m, showed an increase in biological control. Although there was some indication of enhancement of the interaction between adult H. axyridis and spirea aphids, there was no overall detectable increase in biological control by adding alternative food resources in the form of peach trees bearing extrafloral nectar.