View source for Double square-spot

{{Short description|Species of moth}}
{{Hatnote|"Xestia rhomboidea" and variants redirect here; these names were often misapplied to the square-spotted clay ''[[Xestia stigmatica]]''.}}
{{Speciesbox
| image = Xestia triangulum FvL.jpg
| image_caption = 
| taxon = Xestia triangulum
| authority = ([[Johann Siegfried Hufnagel|Hufnagel]], 1766)
| synonyms = 
''Phalaena (Noctua) rhomboidea'' <small>Esper, 1790</small><br />
''Xestia rhomboidea'' <small>(Esper, 1790)</small>
}}

The '''double square-spot''' (''Xestia triangulum'') is a [[moth]] of the family [[Noctuidae]]. It is distributed through most of [[Europe]] except  the Mediterranean islands and northernmost Fennoscandia. In the East, the species ranges East across the [[Palearctic]] to [[Siberia]] and in the South-East to the [[Black Sea]] and in [[Iran]]. It rises to a height of about {{convert|2000|metres}} in the [[Alps]].
[[Image:Rups van driehoekuil op aardappelblad (Xestia triangulum on Solanun tuberosum leave).jpg|thumb|left|200px|Caterpillar]]

This species has pale brown forewings marked with two distinctive black marks. Despite the common name, only one of these is square, the other being roughly triangular. The hindwings are similar in colour to the forewings. It is very similar to ''[[Xestia ditrapezium]]''.

Differences:
*''Xestia ditrapezium'' Front wing on average narrower (or longer). Ground colour of the forewings usually darker (red to violet-brown) and colour of the rear wing a shade lighter. Hindwings are significantly lighter than the Forewings.Collar without contrasts, almost monochrome.
*''Xestia triangulum'' Forewings average wider (or shorter). Ground colour of the forewings of usually lighter (ochre to tawny or grayish brown) colour of the hindwings usually slightly darker grey. Hindwings about as light as the front wings. Lower part of the neck collar grey, separated by a light line from the dark upper.

Technical description and variation: The [[wingspan]] is {{cvt|36|-|46|mm}}. Forewing grey brown, with a rufous tinge: a small blotch at base, a preapical costal spot, and the cell prominently black brown; hindwing fuscous.<ref>Seitz, A. Ed., 1914 ''Die Großschmetterlinge der Erde'', Verlag Alfred Kernen, Stuttgart Band 3: Abt. 1, Die Großschmetterlinge des palaearktischen Faunengebietes, Die palaearktischen eulenartigen Nachtfalter, 1914</ref>

The moth flies at night in June and July in the [[British Isles]]. It is attracted to light and sugar and to [[flower]]s such as [[Teucrium scorodonia|wood sage]].

The [[larva]] is ochreous brown, black speckled; the lines pale; a row of oblique dark subdorsal bars. It is [[List of feeding behaviours|polyphagous]], feeding on a wide variety of plants including [[birch]], [[blackthorn]], [[bramble]], [[Rumex|dock]], [[Crataegus|hawthorn]], [[raspberry]] and [[Goat willow|sallow]]. The species overwinters as a larva.

Inhabits preferably forest edges, slopes covered with shrubs, heaths and gardens and parkland.

== References ==
{{Reflist}}
*Chinery, M. ''Collins Guide to the Insects of Britain and Western Europe''. 1986 (Reprinted 1991)
*Skinner, B. ''Colour Identification Guide to Moths of the British Isles''. 1984

==External links==
{{Commons category|Xestia triangulum}}
*[http://www.lepiforum.de/lepiwiki.pl?Xestia_Triangulum Lepiforum]
* [http://www.nic.funet.fi/pub/sci/bio/life/insecta/lepidoptera/ditrysia/noctuoidea/noctuidae/noctuinae/xestia/ Funet]
* [https://fauna-eu.org/ Fauna Europaea]

{{Taxonbar|from=Q2097524}}

[[Category:Xestia]]
[[Category:Moths described in 1766]]
[[Category:Moths of Europe]]
[[Category:Moths of Asia]]
[[Category:Taxa named by Johann Siegfried Hufnagel]]