Hydrelia flammeolaria, the small yellow wave, is a moth of the Geometridae family. It is found in most of the Palearctic ecozone, from western Europe to Japan. The wingspan is 14–20 mm. There is one generation per year, with adults on wing from mid May to August. The larvae feed on various deciduous trees, including Alnus (including Alnus glutinosa and Alnus incana) and Acer (including Acer campestris) species. Larvae can be found from July to September. It overwinters as a pupa.