The silver Y (''Autographa gamma'') is a migratory

moth Moths are a group of insects that includes all members of the order Lepidoptera that are not Butterfly, butterflies. They were previously classified as suborder Heterocera, but the group is Paraphyly, paraphyletic with respect to butterflies (s ...

of the family

Noctuidae The Noctuidae, commonly known as owlet moths, cutworms or armyworms, are a family (biology), family of moths. Taxonomically, they are considered the most controversial family in the superfamily Noctuoidea because many of the clades are constantly ...

which is named for the silvery Y-shaped mark on each of its

forewing Insect wings are adult outgrowths of the insect exoskeleton that enable insects to fly. They are found on the second and third thoracic segments (the mesothorax and metathorax), and the two pairs are often referred to as the forewings and hindwi ...

Description

The silver Y is a medium-sized moth with a wingspan of 30 to 45 mm. The wings are intricately patterned with various shades of brown and grey providing excellent

camouflage Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the b ...

. In the centre of each forewing there is a silver-coloured mark shaped like a lower case Y () or a lower case Greek letter

gamma Gamma (; uppercase , lowercase ; ) is the third letter of the Greek alphabet. In the system of Greek numerals it has a value of 3. In Ancient Greek, the letter gamma represented a voiced velar stop . In Modern Greek, this letter normally repr ...

(). There are several different forms with varying colours depending on the climate in which the

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e grow.

Technical description and variation

''P. gamma'' Forewing purplish grey, with darker suffusion in places; the lines pale silvery edged on both sides with dark fuscous, the outer line indented on vein 2 and submedian fold, as in ''circumflexa''; the oblique orbicular and the reniform conversely oblique and constricted in middle, both edged with silvery: the median area below middle blackish, containing a silvery gamma; the subterminal dentate and indented, preceded by a darker shade; hindwing brownish grey with darker veins and a broad blackish terminal border: aberrations due to difference in ground colour are ab. ''pallida'' Tutt, in which the ground colour is whitish grey, with the markings appearing darker and more sharply defined; ab. ''rufescens'' Tutt where it is yellowish red, with the gamma mark pale golden, also the lines and edges of stigmata, and the whole underside reddish: and ab. ''nigricans'' Spul., in which the whole forewing up to the pale terminal space is violet black brown; in the ab. ''purpurissa'' ab. nov. (65a) the ground colour is deep olive brown; the inner and outer lines violet, the latter double; subterminal line lustrous violet, irregularly waved and below the middle forming a strong W-shaped mark; the gamma mark is pale golden, and the edges of the dark stigmata are, like the inner line, finely lustrous; a pale violet terminal stripe before termen; hindwing bronzy brownish, with broad dark terminal border. The example from which this description was made, now in the Tring Museum, was taken in Sussex, on the South Coast of England, and is referred to by Tutt in British Noctuae, Vol. IV, p. 32; lastly, the form ''gammina'' Stgr., from Syria and

Pontus Pontus or Pontos may refer to: * Short Latin name for the Pontus Euxinus, the Greek name for the Black Sea (aka the Euxine sea) * Pontus (mythology), a sea god in Greek mythology * Pontus (region), on the southern coast of the Black Sea, in modern ...

, is only half as large as typical ''gamma'', with more definitely marked forewings. Larva pale green, with fine whitish or yellowish, partly double, lines; a straight yellowish lateral line above the white black-ringed spiracles.

Distribution

The species is widespread across

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

and over almost all the

Palearctic The Palearctic or Palaearctic is a biogeographic realm of the Earth, the largest of eight. Confined almost entirely to the Eastern Hemisphere, it stretches across Europe and Asia, north of the foothills of the Himalayas, and North Africa. Th ...

including

North Africa North Africa (sometimes Northern Africa) is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region. However, it is sometimes defined as stretching from the Atlantic shores of t ...

. It is resident in the south of its range and adults fly almost throughout the year. In spring variable numbers migrate north reaching as far as

Iceland Iceland is a Nordic countries, Nordic island country between the Atlantic Ocean, North Atlantic and Arctic Oceans, on the Mid-Atlantic Ridge between North America and Europe. It is culturally and politically linked with Europe and is the regi ...

Greenland Greenland is an autonomous territory in the Danish Realm, Kingdom of Denmark. It is by far the largest geographically of three constituent parts of the kingdom; the other two are metropolitan Denmark and the Faroe Islands. Citizens of Greenlan ...

, and

Finland Finland, officially the Republic of Finland, is a Nordic country in Northern Europe. It borders Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of Bothnia to the west and the Gulf of Finland to the south, ...

with huge invasions taking place in some years. A second wave of migrants arrives in the summer. In

central Europe Central Europe is a geographical region of Europe between Eastern Europe, Eastern, Southern Europe, Southern, Western Europe, Western and Northern Europe, Northern Europe. Central Europe is known for its cultural diversity; however, countries in ...

and the

British Isles The British Isles are an archipelago in the Atlantic Ocean, North Atlantic Ocean off the north-western coast of continental Europe, consisting of the islands of Great Britain, Ireland, the Isle of Man, the Inner Hebrides, Inner and Outer Hebr ...

adults are present in significant numbers from May onwards with numbers dwindling in late autumn as they are killed off by frosts. Some individuals fly south again to winter around the

Mediterranean The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern ...

and

Black Black is a color that results from the absence or complete absorption of visible light. It is an achromatic color, without chroma, like white and grey. It is often used symbolically or figuratively to represent darkness.Eva Heller, ''P ...

seas. It occurs in a wide variety of habitats, particularly open areas. It regularly visits gardens to take nectar from the flowers.

Life history

Silver Y moths can produce two or three

generation A generation is all of the people born and living at about the same time, regarded collectively. It also is "the average period, generally considered to be about 20–⁠30 years, during which children are born and grow up, become adults, and b ...

s in a year with a fourth generation when conditions are particularly good. The eggs are laid on the upper or lower surface of leaves. They are whitish in colour and hemispherical in shape with deep ribbing. They hatch after three to four days (longer in cool conditions). The larvae are about 30 mm long, have three pairs of

proleg A proleg is a small, fleshy, stub structure found on the ventral surface of the abdomen of most larval forms of insects of the Order (biology), order Lepidoptera, though they can also be found on larvae of insects such as symphyta, sawflies. In ...

s and are usually green with whitish markings. They feed on a wide variety of low-growing plants and have been recorded on over 200 different species including

crop A crop is a plant that can be grown and harvested extensively for profit or subsistence. In other words, a crop is a plant or plant product that is grown for a specific purpose such as food, Fiber, fibre, or fuel. When plants of the same spe ...

s such as the

garden pea Pea (''pisum'' in Latin) is a pulse or fodder crop, but the word often refers to the seed or sometimes the pod of this flowering plant species. Peas are eaten as a vegetable. Carl Linnaeus gave the species the scientific name ''Pisum sativum' ...

(''Pisum sativum''),

sugar beet A sugar beet is a plant whose root contains a high concentration of sucrose and that is grown commercially for sugar production. In plant breeding, it is known as the Altissima cultivar group of the common beet (''Beta vulgaris''). Together with ...

(''Beta vulgaris'') and

cabbage Cabbage, comprising several cultivars of '' Brassica oleracea'', is a leafy green, red (purple), or white (pale green) biennial plant grown as an annual vegetable crop for its dense-leaved heads. It is descended from the wild cabbage ( ''B.& ...

(''Brassica oleracea''). They can reduce crop yields by damaging leaves and are often considered to be a pest. The

pupa A pupa (; : pupae) is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their life cycle, the stages th ...

is green at first, gradually darkening to black. The adults mate one or two days after emerging from the pupa and start laying eggs one to five days later. They die three to nineteen days after emergence.

Gallery

File:Autographa gamma en Trachelospermum jasminoides - 01.jpg, On ''

Trachelospermum jasminoides ''Trachelospermum jasminoides'' is a species of flowering plant in the family Apocynaceae, native to eastern and southeastern Asia (Japan, Korea, southern China and Vietnam). Common names include Confederate jasmine, star jasmine, Confederate jes ...

'' File:Autographa gamma-01 (xndr).jpg, ''A. gamma'' profile File:Autographa gamma.o1.jpg, ''A. gamma'' mounted specimen File:Gamma-uil op wortel zijkant (Autographa gamma on Daucus carota).jpg, Caterpillar on carrot (''Daucus carota'') stem File:Autographa gamma-pjt.jpg, Close-up frontal view File:Autographa gamma - 2013-08-04.webm, video of ''Autographa gamma'' in Hesse, Germany

References

* Sarah Broo
Silver Y ''Autographa gamma'' Linnaeus
Butterfly Conservation (retrieved 06/02/07) * Robert C. Venette, Erica E. Davis, Holly Heisler, & Margaret Larson (2003
''Mini Risk Assessment - Silver Y Moth, Autographa gamma (L.)''
(retrieved 29 MAR 2012) * Paul Waring & Martin Townsend (2004) ''Field Guide to the Moths of Great Britain and Ireland'', British Wildlife Publishing, Hampshire.

External links

Silver Y on UKmoths

Taxonomy
Fauna Europaea

Lepiforum.de
{{Taxonbar, from=Q839039 Plusiini Agricultural pest insects Animal migration Moths described in 1758 Moths of Africa Moths of Asia Moths of Europe Taxa named by Carl Linnaeus Articles containing video clips