About Apatura ilia metis Frey, 1829
Apatura ilia metis is a subspecies of butterfly first described by Frey in 1829. Females have a wingspan of 55–60 mm (2.2–2.4 in), while males have a wingspan of 60–70 mm (2.4–2.8 in). The upper side of the wings is dark brown; males have metallic blue-violet hues. This upper side features a clear postdiscal band on the hind wing and several light spots on the fore wing. These light markings appear in two forms: they are white in the nominal form ilia, and clear fawn in the form clytie. For both forms, the fore wing also has an orange-coloured ocellus, which allows differentiation from the related species Apatura iris. A similar ocellus is present on the hind wing in both species. The reverse side of the fore wing is brown, and the back of the hind wing is dull brown with an orange ocellus centered in black, matching A. iris. Seitz's description of mounted A. ilia notes the distal margin of the forewing is obtusely angulate below the apex; the anal area of this wing has a yellowish-ringed ocellus, and the median band of the hindwing has no tooth-like projection on the outer side. Males have a violet gloss, while females are dull black-brown or grey-brown, with pure white bands and spots in both sexes of the nominal form. The species is very variable in colour and pattern; males may sometimes have a pure blue sheen instead of violet, just as in A. iris. Multiple aberrant forms have been described: ab. iliona Schultz is a rare female form with normally developed markings that have a yellowish tint, and no marginal spots on the hindwing, unlike dark clytie specimens. ab. distincta Schultz has the hindwing band separated into isolated spots by broad ground-colour vein streaks. ab. pallescens Schultz refers to paler specimens of both sexes with pale ashy-grey ground-colour and only weak gloss in males; the underside is paler with a yellowish tint, most specimens appear to be artificial products of temperature experiments, though similar individuals are occasionally found in the wild. ab. inspersa Schultz has bands and spots on both wings shaded with sooty-black, without the markings disappearing or becoming diffuse. ab. iliades Mitis is black with no markings other than possible white subapical spots on the forewing; males have a blue sheen, and it occurs alongside the main form across its range, with extreme and intermediate forms mostly found in males, and more rarely in females. ab. asta Schultz has otherwise normal specimens with yellowish spots in the anal angle of the forewing, a brownish macular band at the margin of the hindwing, and brownish smears between this band and the white median band; this form somewhat resembles Apatura metis bunea. ab. magnifica Schultz is distinguished by a broad yellow margin traversed by black veins. The male type has other white markings heavily covered in sooty colour matching ab. inspersa. A related female form has ivory-coloured spots and median bands on a very dark ground, and a broadly brownish outer margin on the hindwing. It is rare in nature, and is also known as a product of temperature experiments. ab. clytie is a form where all normally occurring markings except the forewing subapical spots are brownish, and the hindwing has a brownish, entire or macular, submarginal band. It occurs alongside the main form everywhere, with ground-colour varying between lighter and darker tints in transitions to the main form. Some specimens approach or match the brown local races discussed below, and these brown forms are locally prevalent or the only form in southern districts of the species' range, merging into the brown subspecies. ab. astasioides Stgr. has all or almost all brown bands and spots of the upperside absent, holding the same position among clytie that ab. iliades holds among ilia, and occurs here and there alongside the main form. ab. phryne Aigner is a transition towards ab. astasioides, with reddish brown and vestigial markings in the central area of the forewing, a submarginal macular band on the hindwing, and the median band; it has been recorded from Hungary and other countries alongside clytie. Mature larvae of the species are 4–5 cm long, and are dirty green. They are similar in shape and markings to larvae of A. iris, but have reddish horns on the head with a black stripe, a yellow line edged in red along each side of the anterior body, and five yellow oblique stripes edged red that each extend over two segments on each side of the body from the centre backwards; anal processes and legs are blue-green. Larval habits are similar to those of A. iris; larvae feed especially on Populus tremida, P. pyramidalis, and various willows including Salix caprea, S. viminalis and S. rosmarinifolia. The pupa is greenish, with a keeled dorsal surface; the back, wing-cases and head processes are edged with yellow. Butterfly habits are similar to those of A. iris. The nominotypical subspecies, with the individual forms listed above, is distributed across Germany, Belgium, France, Switzerland, Austria, Bosnia, Serbia, western and northern Hungary, Finland, the Baltic Provinces of Russia, and South Russia (Volga districts). As noted, the white-marked nominal form becomes less abundant in certain southern districts of West and Central Europe, where brown specimens are the prevalent or only form, and form distinct local subspecies. A notable exception is Portugal, where a white-spotted very similar to the northern form occurs; this subspecies, lusitanica, is characterized by enlarged white spots at the forewing eye-spot, and a row of small brownish spots on the hindwing between the whitish submarginal spots and the median band, similar to ab. asta. This subspecies is recorded from Porto, Portugal, and is the southernmost known race of the species. Two named brown subspecies exist: eos Rossi and budensis Fuchs. In eos, the dark ground-colour is paler overall, shaded and dusted with brown especially at the wing bases, violet gloss is almost entirely absent, ochre-yellow markings are dilated and sometimes ill-defined, and a row of roundish black-brown spots that shade off proximally is present near the light submarginal band on the hindwing; it occurs in southern France (Provence) and Northern Italy. The second race, budensis Fuchs, is similar to eos; it entirely lacks blue gloss, and has a bright yellow basal area on the hindwing. The dark wing border that is usually present in clytie is sometimes absent, or replaced by a heavy brown-grey arched stripe. It occurs in Hungary, especially from Budapest southward and eastward, and is less constant and characteristic toward the north, where it transitions to clytie and sometimes approaches eos in colouration. It is also known from Bulgaria and the Bukovina, and has sometimes been incorrectly considered identical with metis Frey. The lightest form of the species is here Fldr. In males, the remaining dark areas of the wings have a faint violet sheen, and the entire wing gains a brilliant red-violet gloss when viewed at an acute angle. The median band of the hindwing is sometimes so dilated toward the distal margin that it merges with the submarginal band to form a deep ochre-yellow area bearing a row of isolated rounded dark spots, with faint dark shadows radiating basad from these spots. However, some individuals, especially females, have the middle band separated from the submarginal band by a grey-brown area, with the submarginal band being very broad and completely continuous in this case. A distinct female form of this race has whitish bands and spots, a light ochreous wing ground with only faint dark shading scattered across it, and reduced, small, roundish and entirely isolated dark spots on the hindwing; this is female-ab. sobrina form. nov. found in Eastern Central and North China. A record of this form from Japan is considered erroneous. Darker individuals with whitish bands (or partly whitish bands on the forewing) that approach serarum Oberth. occur alongside the yellow main form not only in West China, but also in the Shan-States and Upper Burma, with apparently identical specimens found there. The subspecies serarum Oberthür has a dark ground-colour, a deep blue sheen in males, white markings, broadened bands that are straight on the hindwing, and sharply defined edges on both sides; the hindwing bears a row of small whitish submarginal spots. Females have a paler ground-colour without gloss. It occurs in West China (Ta-tsien-lu, Omei-shan, etc.), Central China (Chang-yang), and Yunnan. A distinct form found in the most southern districts of Russia is characterized by the loss of eye-spots in the anal area of both the hindwing and forewing, while the hindwing band retains its original width and becomes more sharply defined; this form is metis Frr., which is treated as either a full species or a subspecies of A. ilia. It is somewhat smaller than typical specimens of the species, has more sharply angled wings, all markings are ochreous (as in clytie) and more or less extended. The ocellus-like spot is sometimes completely absent from the hindwing, and is usually reduced to a dot on the forewing. Females are paler, with more or less extensive yellow dusting. An alternate form occurs alongside this main metis form, where only the submarginal band of the hindwing and certain outer spots on the forewing are golden yellow, while the central area markings remain white; this is ab. bunea H.-Schiff., which appears to only occur in males. Thirdly, specimens of both sexes exist that match the main ilia form with white markings, and only have a row of obsolescent whitish spots at the margin of the hindwing; this form is named gertraudis form. nov., which is treated as either a full species or a form of ssp. bunea. It is easily distinguished from ilia by the even width and sharp definition of the hindwing band, and reduced anal ocelli; female ground-colour is more or less dark, sometimes almost ashy grey, with diffuse markings. Finally, the name coelestina Gr.- Grsh. refers to male main-form metis that have a stronger, delicate sky-blue rather than violet gloss on the upperside; in this form the light marginal band of the hindwing is broadened and united with adjacent spots. It occurs in South-East Russia (Sarepta), the Caucasus, and the Altai. In Japan, the species is represented by substituta Btlr., which is very similar to metis and often confused with it. This form generally has a darker ground-colour, the eye-like spots of both wings are not obsolescent, the submarginal spots of the hindwing are elongate-ovate or rounded-quadrate (rather than arrowhead-shaped or luniform as in metis), and the hindwing band on the underside is more distinctly white and contrasts with the ground. Some specimens from Korea have whitish bands on the upperside, resembling bunea. Observations of this Japanese race note that the butterflies prefer to circle around the tops of tall willows, where their larvae feed, and occasionally descend to damp roadside areas or rest on the leaves of their host tree. The green pupa is similar in shape and colour to a young willow leaf. This form varies in colour depth, and is more abundant in the mountains than the plains. It is found in Tokio, on Asamayama and Oyama, and in Hokaido; it is also recorded from North China, Korea, the Amur region, Askold, Suifun and Su-chan. This species is present across most of Europe and through the Palearctic to Japan. However, it is absent from European Mediterranean islands, the southernmost regions of Europe, most of Spain and Portugal, southern Italy and Greece, as well as Nordic countries (Denmark, Sweden, Norway), Poland, northern Germany and the British Isles. This species was one of 35 European butterflies that ecologists had sufficient data for to study potential range shifts across Europe. Among these 35 studied butterflies, Apatura ilia is exceptional: it is the only species whose northern range limit has shifted slightly south, while its southern limit has remained stable.
