Ovipositional site selection is a crucial moment for female seed parasitoids as host resources are limited and subject to increased competition. Also, a seed must be of good quality in order to provide the offspring with sufficient food and space. Curculio glandium Marsham, 1802 (Coleoptera: Curculionidae) females oviposit into premature acorns, wherein larvae develop. Parasitized fruits are not chemically marked. Instead, females display opportunistic behaviors and are prone to oviposit into pierced or cracked acorns, to save the effort of drilling. Our aim was to reveal whether opportunism of C. glandium includes oviposition into acorns with channels drilled by another female and, if so, whether encountered eggs are consumed prior to the new oviposition. Females were given alternatives: I) fresh or egg-parasitized and II) egg-parasitized or naturally cracked acorns. Subsequently, paired individuals were enabled to lay eggs into acorns with: I) single and II) two pierced holes. Females preferred exploited acorns over intact (p < 0.001) while no difference was found between egg-parasitized and cracked (p = 0.47). The median number of eggs in the shared channel was significantly lower than in the separate channels combined (p = 0.0001). Results indicate that the potential consequences of oviposition in parasitized seeds (overpopulated acorns) seem to be prevented by egg consumption. In the context of no host-marking behavior, it can be interpreted as a means of diminishing future scramble competition between unrelated offspring.