Immature insects that develop within plant structures entirely of their parent’s choosing are dependent on those parents to select suitable hosts. Weevils that develop within tree fruits are an obvious example of this situation. We examined oviposition choice by the black walnut curculio, Conotrachelus retentus (Say), in a walnut plantation setting for 10 yr, focusing on the effects of cluster size on oviposition. The percentage of nut clusters with curculio oviposition did not differ significantly among cluster sizes, although the percentage of individual nuts destroyed was significantly lower in single nuts compared with two-nut clusters. Our data support the hypothesis that the curculio behaves as though the nut cluster was the ecological unit for oviposition, as do other weevils such as the pecan weevil.