''Mesotype didymata'', the twin-spot carpet, is a moth of the family Geometridae. The species was first described by Carl Linnaeus in his 1758 10th edition of ''Systema Naturae''. Its genus is sometimes included in ''

Perizoma ''Perizoma'' is a genus in the geometer moth family (Geometridae). It is the type genus of tribe Perizomini in subfamily Larentiinae. The tribe is considered monotypic by those who include the genera '' Gagitodes'', '' Martania'' and '' Mesotyp ...

''.

Distribution

It is found in northern and central Europe; further south and east it seems to be confined to the mountains Pyrenees, Alps, Urals.

Description

The wingspan is 24–29 mm. The ground colour of the forewings is generally pale or dark grey. There are two dark stains near the apex and the costa of the forewing. The wavy crosslines delimit a darker mid field and a darker marginal field. It is very variable in colour, with the male considerably darker than the female; in some districts the sexual dimorphism is quite striking. This sex is also appreciably smaller and narrower-winged than the male and has a much stouter abdomen. - ab. ''ochroleucata'' Auriv. is unicolorous grey yellow or yellow brown without markings except the light subterminal line. - In ab. ''nigrofasciata'' Rbl. The ground colour is darkened and the median band narrow, almost black. - ab. ''nigra'' Prout has uniform blackish brown wings. In ''hethlandica'' Rbl. the male is more or less bright orange brown, the female lighter ochreous brown or fawn colour. Prout, L. B. (1912–16). Geometridae. In A. Seitz (ed.) ''The Macrolepidoptera of the World''. The Palaearctic Geometridae, 4. 479 pp. Alfred Kernen, Stuttgart. The larva is long and slender and differs so from most species of the genus ''

''. It is grey-green in colour with short, dark brushes.

Biology

Adults are on wing from June to August. There is one generation per year. The larvae feed on various plants, including ''

Vaccinium myrtillus ''Vaccinium myrtillus'' or European blueberry is a holarctic species of shrub with edible fruit of blue color, known by the common names bilberry, blaeberry, wimberry, and whortleberry. It is more precisely called common bilberry or blue whortle ...

'', '' Salix'' and '' Calluna''.Unlike most ''Perizoma'' the species lives openly on the nutrient plant, not inside the seed capsules, and it can use a variety of different nutrient plants. This may provide the basis for assigning this species (and some others) to the genus ''Mesotype''.

Subspecies

*''Mesotype didymata didymata'' *''Mesotype didymata hethlandica'' (Shetland Isles)

References

External links

Twin-spot Carpet at ''UKMoths''''Lepiforum e.V.''
Perizomini Moths of Europe Taxa named by Carl Linnaeus {{Larentiinae-stub