This study focuses on the effect of beaver presence on aquatic insect emergence and potential secondary effect on a possible predator of emerging insects on land, the European pied flycatcher nesting success in boreal headwater lakes in Finland. We focus on i) a clearwater lake shore habitat, ii) a beaver pond and iii) their related non-shore forested control sites; evaluate the abundance and biomass of aquatic emergent and terrestrial flying insects and correlate them as prey availability of the target species on terrestrial habitats: to the European pied flycatcher.