Length 2–4 mm.
The species differs from other species of Hedychridium by its smaller size and almost completely green or bluish body, which occasionally has weak golden reflections dorsally on the mesosoma. The tarsi are pale brown. Exceptionally small and greenish males of H. ardens can resemble H. zelleri, but they have sparser and coarser punctation dorsally on the mesosoma.
West Palearctic: northern and central Europe (Linsenmaier 1959).
Habitat: sparsely vegetated sandy areas, usually near seashore. Adults are occasionally found on flowers.
Flight period: late June to early August.
Host: species of Miscophus Jurine (Crabronidae) (Müller 1918, Saure 1998, our own obs.). In central Europe, possibly also Diodontus tristis (Vander Linden) and D. minutus (Fabricius) (Jacobs and Kornmilch 2007).