According to foraging theory, female parasitoids should alter their host choice in response to cues that indicate a limitation of resources. We tested whether females of the polyembryonic parasitoid Ageniaspis fuscicollis (Hymenoptera: Encyrtidae), which attack egg batches of small ermine moths (Lepidoptera: Yponomeutidae), would alter their host acceptance pattern in response to different pre-patch experience. We kept females of the parasitoid prior to a patch visit under different conditions, which should indicate different levels of competition for hosts. With increased competition as pre-patch experience, females laid more eggs per host egg and self-superparasitized more often, and the resultant egg distributions showed a trend from more regular distributions to increasingly Poisson and aggregated distributions. Consequently, females with a pre-patch experience that would indicate low competition for hosts had the most even egg distributions. We conclude that pre-patch experience of competitors may lead to a significant change of mutual interference patterns in egg-laying A. fuscicollis wasps.