Abstract We investigated the ability of the pupal parasitoid Pimpla turionellaeto find a simulated host (cigarette filters) hidden within paper cylinders. A pronounced concentration of ovipositor insertions on the concealed filter demonstrated the ability of the parasitoid to locate hidden hosts in the absence of chemical and visual cues. On the basis of laser–Doppler vibrometer studies, we assume that the parasitoid uses self-produced vibrations to locate the filter within the paper cylinder. Parasitoids showed this ability with cylinders made out of 17, 48, and 80 g paper. However, the total number of ovipositor insertions decreased with increasing paper weight. Based on these results, we propose that ovipositor insertion by P. turionellaemight be induced by the contrast in resonance between hollow and solid sections of the substrate, rather than by the solidity of the substrate as such. We discuss this form of vibrational sounding as an additional solution to the reliability–detectability problem faced by host seeking (pupal) parasitoids.