| White-letter hairstreak | |
|---|---|
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Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Lepidoptera |
| Family: | Lycaenidae |
| Genus: | Satyrium |
| Species: | S. w-album |
| Binomial name | |
| Satyrium w-album (Knoch, 1782) | |
The white-letter hairstreak (Satyrium w-album) is a butterfly in the family Lycaenidae.
A dark little butterfly that spends the majority of its life in the tree tops, feeding on honeydew, making it best observed through binoculars. The uppersides are a dark brown with a small orange spot in the bottom corner of the hindwing. The male has a small pale spot on the forewings made up of scent scales. The undersides are a lighter brown with a thin white line, the "hairstreak", which gives this group of butterflies their name. On the hindwing this streak zigzags to form a letter W (or M) from which this species gets its name. The outer edge of the hindwing has an orange border, but there is no orange on the forewings as on the similar black hairstreak and there are two short tails, the female's longer than the male's on the hindwings. Part of a group known as "lateral baskers", they always rest with their wings closed, usually at right-angles to the sun during day.
T. w-album Knoch (72 h). Above similar to unicolorous specimens of spini ; the white band of the hindwing beneath commences more proximally. about the middle of the costal margin, and runs straight to the base of the tail, forming here a W. Before the margin of the hindwing a bright red undulate band. Central, Northern and Eastern Europe and Anterior Asia. In ab. butlerovi Krul. the white band of the hindwing beneath is posteriorly obsolete, there being no white W. On the other hand, ab. albovirgata Tutt has the white band much wider, reaching on the hindwing to the red submarginal band; there occur also transitions towards this aberration (semialbovirgata), with the band widened in parts. — sutschani Tutt [now subspecies] resembles the nymotypical form, but the underside is paler grey and is variegated with small white spots at the red band ; from Sutchan. — fentoni Btlr. [now subspecies] is coloured above like European specimens, but agrees with spini in size, and the submarginal spots of the hindwing beneath are orange instead of red; North Island of Japan (Hokkaido). — Egg semiglobular, red-brown, with white reticulation; as a rule deposited in pairs on elm. Larva until June, adult light green, with thin small oblique subdorsal stripes and brownish head:it generally takes such a position on the underside of a leaf that it resembles a small fresh leaf or a fold between the ribs. Pupating on the trunk or close to the ground; often the sexes meet already as larvae and pupate near one another, the male behind the female (Voelschow). Pupa yellowish brown, with darker wing cases. The butterflies occur in July and August and are rather local. On certain days I have seen towards 11 o'clock some numbers come down from the tree-tops to the road where they settled in the dust, not on damp places. As they could not find a firm hold, they frequently tumbled over and remained lying sideways in the sun. Otherwise singly near woods and in avenues of elm-trees. [1]
The insect has a widely disjunct distribution across the Northern Hemisphere; it is found throughout much of Europe, from Wales to the Urals, southern Scandinavia to the Mediterranean, and again in Siberia, the Russian Far East, Korea, and Japan. It has not been reported from the Himalaya, despite the occurrence of four species of elm there. [2] The species is also absent from North America.
It is widely but patchily distributed across most of England; the butterfly is absent from Ireland, western Wales and most of Cornwall. In 2017, the butterfly was spotted in Scotland again after a gap of 133 years. [3] The spread of second, far more lethal, strain of Dutch elm disease in the 1970s inevitably had a major impact on the British population, but it has since recovered well in places and is still increasing its range.
To safeguard the future of this butterfly, some conservation organisations within the UK, such as the Hampshire and Isle of Wight branch of Butterfly Conservation and the Forestry Commission, have planted disease-resistant cultivars, notably Lutece. [4] The beetle-resistant European white elm has also been widely planted, notably by the Cheshire Wildlife Trust.
Eggs are laid singly, usually on the girdle scars near the terminal buds of elm trees. Unlike other hairstreak eggs, white-letter hairstreak eggs are harder to find during the winter months as they are flatter, turn brown with age, and are thus far less distinct on the twigs. Wych elm is reputedly preferred, but field elm and European white elm are also used, as are Asiatic species, notably Japanese and Siberian elm, as well as hybrid cultivars such as Lutèce. The caterpillar hatches in March. Under normal circumstances, where sexually-mature trees occur, it immediately feeds on the flowers, later the seeds, before progressing to the emergent leaves in April. However, research in the Low Countries has shown that the larvae are remarkably adept at using non-flowering suckers; provided they are able to hydrate on emergence, they can survive dormant for up to six weeks, until the leaves flush. The larval stage lasts on average for 57 days, but this can vary from 37 to 78 days, depending on food availability. [5]
Pupation takes place underneath a leaf or twig, or in a bark crevice. Adults are on the wing from late June until the middle of August in the UK, where there is one brood a year. The butterflies occasionally fly down from the canopies to nectar from flowers when honeydew is unavailable, notably after heavy rains have washed it from the leaves. The much-preferred flower observed in the UK is creeping thistle, but bramble and others are also used. In France, the butterfly has been observed nectaring on Buddleja davidii , [6] but the flowers of the lime tree appear to be its favourite. [7]
The brown hairstreak is a butterfly in the family Lycaenidae. The range includes most of the Palaearctic.
The purple hairstreak is a butterfly in the family Lycaenidae distributed throughout much of Europe, North Africa, Anatolia, Caucasia, and Transcaucasia. The larva feeds on Quercus robur, Quercus petraea, Quercus cerris and Quercus ilex.
The black hairstreak is a butterfly in the family Lycaenidae.
Ulmus 'Nanguen' is a complex fourth generation Dutch hybrid cultivar raised at the Dorschkamp Research Institute for Forestry & Landscape Planning, Wageningen. Lutèce was derived from the cross 'Plantyn' ×, an ancestry comprising four field elms, a wych elm, the curious Exeter Elm ('Exoniensis'), and a frost-resistant selection of the Himalayan elm.
Ulmus 'New Horizon' is an American hybrid cultivar raised by the Wisconsin Alumni Research Foundation (WARF), from a crossing of the Japanese Elm clone W43-8 = 'Reseda' with Siberian Elm clone W426 grown from seed collected from a street tree at Yankton, South Dakota. Tested in the US National Elm Trial coordinated by Colorado State University, 'New Horizon' averaged a survival rate of 74% after 10 years.'New Horizon' was patented in the US in 1994, while in Europe, it is marketed as one of the 'Resista' elms protected under EU breeders' rights.
Ulmus 'Sapporo Autumn Gold' is one of the most commercially successful hybrid elm cultivars ever marketed, widely planted across North America and western Europe, although it has now been largely supplanted by more recent introductions. Arising from a chance crossing of the Japanese elm and Siberian elm, seed was sent in 1958 by Prof. Nobuku Takahashi and his colleagues at the Sapporo Botanical Garden of Hokkaido University, Sapporo, to Eugene Smalley at the University of Wisconsin–Madison. The patent issued in 1975 has expired, and there are now no propagation restrictions.
Ulmus 'Wanoux' is a Dutch hybrid cultivar raised at the Dorschkamp Research Institute for Forestry & Landscape Planning, Wageningen, from an open pollination of 'Plantyn'. Originally identified as clone No. 762, it was selected for assessment by the French Institut National de la Recherche Agronomique (INRA), which patented it as 'Wanoux' in 2006.
Ulmus 'Arno' is an Italian hybrid cultivar derived from a crossing of 'Plantyn' with the Siberian Elm Ulmus pumila clone S.2. It was raised by the Istituto per la Protezione delle Piante (IPP) in Florence, and released in 2007. However, 'Arno' was not a commercial success; propagation had ceased by 2010, and it is no longer patent protected.
Ulmus 'Fiorente' is a hybrid cultivar elm derived from a crossing of the Siberian Elm Ulmus pumila clone 'S.10' from Lucca, Italy, with the Ulmus minor clone 'C.02' from Lungarno, Florence, by the Istituto per la Protezione delle Piante (IPP), part of the Italian National Research Council, in Florence. 'Fiorente' was patented in 2006, and released to commerce in 2012.
Satyrium spini, the blue spot hairstreak, is a butterfly in the family Lycaenidae.
Satyrium ledereri, the orange banded hairstreak, is a butterfly in the family Lycaenidae.
Ulmus 'Morfeo' is a hybrid elm cultivar raised by the Istituto per la Protezione delle Piante (IPP), Florence, in 2000. 'Morfeo' arose from a crossing of the Dutch hybrid clone '405' and the Chenmou Elm, the latter a small tree from the provinces of Anhui and Jiangsu in eastern China, The '405' clone is a full sister of 'Groeneveld', a crossing of an English U. × hollandica and a French U. minor from the Barbier Nursery, Orléans.
Satyrium californica, the California hairstreak, is a butterfly of the family Lycaenidae. It is found from British Columbia south to southern California and east to Colorado.
Satyrium favonius, the oak hairstreak or southern hairstreak, is a butterfly of the family Lycaenidae. It is found in the United States from southern New England and the Atlantic Coast south to peninsular Florida and west to central Illinois, south-eastern Colorado and the Gulf Coast.
Satyrium acadica, the Acadian hairstreak, is a butterfly of the family Lycaenidae. It is found in North America from British Columbia east to Nova Scotia and south to Idaho, Colorado, the northern Midwest, Maryland, and New Jersey.
Satyrium behrii, the Behr's hairstreak, is a butterfly of the family Lycaenidae. It is found in western North America from western Texas north and west through New Mexico, Arizona, and southern California to British Columbia.
The sylvan hairstreak is a butterfly of the family Lycaenidae. It is found in western North America, from British Columbia south-east to Wyoming, Colorado and New Mexico and south through California to Baja California Norte.
Satyrium liparops, the striped hairstreak, is a butterfly of the family Lycaenidae described by John Eatton Le Conte in 1833. It is found in North America, from the Rocky Mountains south from southern Canada to Colorado, east to Maine and south to Florida.
Satyrium polingi, or Poling's hairstreak, is a butterfly of the family Lycaenidae. It was described by William Barnes and Foster Hendrickson Benjamin in 1926. It is found in North America from southern New Mexico and western Texas south to north-eastern Mexico. The habitat consists of oak woodlands.
Satyrium caryaevorus, the hickory hairstreak, is a butterfly of the family Lycaenidae. It is found in eastern North America, from southern Ontario west to Minnesota and Iowa, south in the Appalachian Mountains to eastern Tennessee.
This article incorporates text from this source, which is in the public domain .