(Alnus), beech (Fagus), birch (Betula) and chestnut (Castanea). The caterpillars of numerous Old World and some North American species feed on the Salicaceae Populus (poplars) and Salix (willows), which belong to the Malpighiales. Less common larval food plants of Catocala are for example elms (Ulmus) and various Rosaceae of the Rosales, Tilia (linden and basswood) of the Malvales, or some Fabaceae of the Fabales; as the preceding, these all belong to the Fabidae lineage of rosid eudicots. More unusually, underwing moth caterpillars have also been found to feed on such plants as maple (Acer) which belongs to a distant lineage of rosids, as well as on such plants as ash trees (Fraxinus) and blueberries (Vaccinium) which are asterids and quite unrelated to the other food plants by eudicot standards. The adults are predominantly nocturnal, flying from shortly after dusk right up to daybreak. They are generally most active about two hours after nightfall. However, several if not all species of underwing moths have a second activity period exactly around noon, during which they are also regularly found on the wing for about 1–2 hours each day. The genus name Catocala roughly means "beautiful hindwings". It is a combination of two Ancient Greek words, kato (κάτω, "the rear one" or "the lower one"), and kalos (καλός, "beautiful"). Classification There are over 250 species in this genus. The species of Catocala are here divided into a Eurasian group, and another one which is found in North America. This does not imply actual relationships; it is mainly done to more conveniently deal with the large number of species. Still, it is not unlikely at all that the groups consist at least to some extent of closely related species. There are several cryptic species complexes in Catocala, e.g. the group around the Delilah underwing (C. delilah); these and other hitherto unknown species are still being discovered and described in some numbers. Thus, resolving the phylogeny and taxonomy of the underwing moths is an ongoing effort, which has made () little progress. In the scientific literature, smaller subdivisions into putatively related species are sometimes applied, but there is no consistent and widely accepted taxonomic treatment for the genus as a whole. Synonyms Several distinct genera have formally been proposed for splitting from Catocala, but these are all treated here as junior synonyms. These synonyms and other invalid names of Catocala are: Andreusia Hampson, 1913 (unjustified