SUMMARY1 Emergent aquatic insects can represent an important subsidy to terrestrial ecosystems but may also transport accumulated contaminants across ecosystem boundaries when larvae develop in contaminated sediments. 2 We sampled tetragnathid spiders (terrestrial predators), larval chironomids (spider prey of aquatic origin) and terrestrial insects (terrestrial prey) from two contaminated and two control sites in the Norfolk Broads (U.K.) to determine whether the organotin compound tributyltin (TBT) is transferred by emergent aquatic insects. TBT, a biocide in antifoulant paints, was prohibited in the U.K. in 1987 and globally since 2008 but persists in sediments for decades. Combining stable-isotope analyses commonly used in ecology with ecotoxicological methods enabled us to test whether aquatic subsidies could transport organotin to terrestrial predators. N-enrichment along this short food chain, chironomid DBT concentrations were significantly greater than those of their spider predators. Biota sediment accumulation factors (sediments to chironomids) and biomagnification factors (chironomids to spiders) were below the thresholds defining the occurrence of bioaccumulation and biomagnification. 5 Although biomagnification was not detected, it is of concern that butyltins are still present in freshwater food webs c. 25 years since last known TBT use in the U.K., and continue to be transferred to terrestrial consumers.