Leptocybe is a monotypic genus of insects in the superfamily Chalcidoidea, the chalcid wasps. It contains the single species Leptocybe invasa, which is known by the common name blue gum chalcid. This chalcid was discovered in 2000 when river red gums (Eucalyptus camaldulensis) in the Middle East and Mediterranean began developing disfiguring galls. The damage became severe enough to cause crop losses in tree plantations. Galls were collected and a previously undescribed species of chalcid wasp emerged. In 2004 it was described to science as Leptocybe invasa.