Pollination–seed predation mutualisms such as moth–yucca interactions are important model systems for studying mechanisms that limit exploitation when mutualistic partners have strong conflicts of interest. In many moth–yucca interactions, oviposition leads to the failure of some ovules to develop normally. Here, we demonstrate that moth eggs almost always perish if they are inside these oviposition-induced ‘damage zones’ of developing fruit. Moreover, because more ovipositions result both in larger damage zones and in higher proportions of eggs within damage zones, this source of mortality is strongly density-dependent. Therefore, mortality of eggs in oviposition-induced damage zones may be an important process for limiting seed consumption and regulating moth densities in many moth–yucca mutualisms.