Combination of harmful-arthropod-attracting compound and natural enemy

[Problem] To provide a system having an excellent attracting effect on harmful arthropods. [Solution] A combination for controlling the behavior of harmful arthropods, comprising at least one compound selected from the group consisting of compounds that are attractive to the harmful arthropods, and at least one natural enemy selected from the group consisting of the natural enemies of the harmful arthropods, wherein the compound and the natural enemy are used in a mode where the harmful arthropods are synergetically attracted.