AbstractStudies of insect movement are hampered by the small size of insects and the associated difficulty in tracking them in the environment. We tested the potential of quantum dots (QDs) to mark large numbers of insects very quickly. Our results demonstrate that green CdTe (cadmium tellurium) QDs were effective markers in the laboratory and can be applied to large numbers of insects very easily. Successful recaptures in the field demonstrate that QDs have great potential as external markers.