Citizen science reveals the establishment of Chamaesphecia empiformis (Esper) (Lepidoptera: Sesiidae), a long-lost biological control agent for Euphorbia cyparissias (Euphorbiaceae), in Ontario, Canada

The European root-boring moth, Chamaesphecia empiformis (Lepidoptera: Sesiidae), was released in Ontario, Canada, in 1971 and 1989 as a biological control agent for the perennial invasive weed cypress spurge, Euphorbia cyparissias Linnaeus (Euphorbiaceae). Until recently, the moth was believed to have failed to establish. Beginning in 2015, images posted on citizen science platforms, including BugGuide, iNaturalist, and Facebook groups, indicated that C. empiformis was in fact established. We have confirmed its presence in eastern Ontario by morphological and molecular identification of field-collected adults and eggs. This may be the longest-known lapse between the release of a weed biological control agent and confirmation of its establishment. Citizen science may provide valuable records documenting the establishment and dispersal of biological control agents.