Measurements:
WS: 44-50mm
Identification:
Deep orange color above makes it characteristic in the Nordic region. Females show pale spots in the black-bordered tips and margins of both upper wings; the male is solid black. Compared to hyale [Gul Høsommerfugl] the black rim covering the forewing tip above is running down along the outer margin in a very solid band, reaching the inner margin, running past the anal corner.
The underside of the forewing shows a deep yellow-orange center resembling the upperwing color, and much warmer than on similar hyale [Gul Høsommerfugl]. The hindwing is deep yellow with a greenish cast, and similar to hyale shows a black spot on the forewing and a white spot centrally on the hindwing. This seems like being double-red-encircled, giving it a more pronounced appearance than on hyale [variable].
Never shows the upperside at rest.
The wing tip of croceus is supposed to be narrower than on hyale [likely variable].
Similar species:
Life stages:
Distribution:
N Africa, S and C Europe, Middle East to W Asia.
Habitat:
In Nordic region, mostly coastal areas. Flower-rich fields.
Behavior:
A strong flyer. In the Mediterranean region it flies all year.
Status:
In Denmark and Nordic region a rare southern singleton visitor, mostly in August. The most widespread Colias species in Europe.
Host plants:
Humle-Sneglebælg (Medicago lupulina) [Black Medick ~ Humlelusern]
Rød-Kløver (Trifolium pratense) [Red Clover ~ Trébol Rojo ~ Rödklöver]
Lucerne (Medicago sativa) [Alfalfa ~ Lucerna ~ Foderlusern]
Almindelig Kællingetand (Lotus corniculatus) [Bird's-foot Trefoil ~ Loto Corniculado ~ Käringtand]
Muse-Vikke (Vicia cracca) [Tufted Vetch ~ Arveja Silvestre ~ Kråkvicker]
Rundbælg (vulneraria) [Common Kidneyvetch ~ Vulneraria ~ Getväppling]
Foder-Esparsette (Onobrychis viciifolia) [Common Sainfoin ~ Esparceta ~Esparsett]
and other plants of the pea-family (Fabaceae).
Feeding plants:
The same as many of the host plants.
Number of generations depends on local conditions.