<p>The field of urban ecology is being transformed by advances in DNA barcoding, genomics and bioinformatics. The advent of environmental DNA (eDNA), in particular, moves beyond the identification of individual species towards the rapid assessment of entire ecosystems. Urban ecology is being transformed through new sampling and sequencing techniques that are reframing the city as an object of study. The increasing emphasis on eDNA presents a notable elaboration of systems-based conceptions of urban ecology but there has been little engagement with the wider implications of these developments for the conceptualization of urban space. Here I outline the prospects for an alternative conceptual synthesis that lies closer to the concerns of the social and historical sciences. I suggest that a closer engagement with the related field of forensic ecologies can provide a methodological bridge between new advances in DNA sequencing and post-positivist approaches to the study of cities.</p>