When selecting a habitat for breeding and offspring rearing, it is optimal for organisms to select a stable habitat with high amounts of quality resources. However, organisms may inadvertently select a habitat for breeding that would initially appear preferential and healthy but may, in reality, be detrimental to parent and/or offspring fitness. Such ecological traps may even be the result of human habitat modification and conservation efforts. In this study, we tested whether migratory European pied flycatcher (Ficedula hypoleuca) offspring cavity-nesting in patches of forest affected by outbreaks of the great web-spinning sawfly (Acantholyda posticalis) incurred fitness detriments characteristic of ecological traps when compared to flycatchers that nested in patches of unaffected forest. Outbreaking sawfly larvae overconsume Scots pine (Pinus sylvestris) needles and substrate, which decreases resource availability directly and indirectly – through cascading effects – for birds inhabiting the forest. In installing nest boxes to attract breeding pairs and potentially combat the outbreak, we found that flycatchers inhabiting areas of sawfly outbreaks had similar clutch sizes to pairs breeding in healthy forest patches. Contrarily, the fledgling number and body condition were significantly lower for those nesting in the damaged forests. Though larvae serve as the primary food source for nestlings, the forest patches damaged by sawflies also had lower larval biomass from rapid resource decline due to overconsumption. In provisioning nest boxes for migrating flycatcher pairs in forest patches that were subsequently impacted by a pest insect outbreak, an ecological trap arose for those pairs choosing to nest in what appeared to be an unaffected forest at first. Given the inability of breeding pairs to distinguish habitat quality on initial inspection, we suggest that nest boxes be used with caution in areas with unstable habitat conditions when attracting migratory birds given the trends of their declining global numbers.