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Species account
Common Blue
(Polyommatus icarus)
Rottemburg (1775)
Hairstreaks and Blues (Lycaenidae)
COBL
24731
Almindelig Blåfugl (dk)
Mariposa Ícaro (es)
Puktörneblåvinge (se)
Measurements:
WS: 21-33mm
Generations:
2-3
Flight period:
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| SE | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Identification:
Middle-sized blue. Sexes differ.
Males are blue above with a narrow black marginal band, with the outer margin bright white. The ribbons above are pale bluish.
The female above is darker, brownish with a bluish body and a blue suffusion radiating out from there. And it shows a row of orange spots running submarginally along both wings.
The underside pattern is similar on both sexes, but the ground color is darker brownish-beige on the female (a general trait of the blue butterflies). Characteristic for icarus is the white wedge that runs midwing from inside the orange spots to the row of black spots proximally.
To separate icarus from agestis (Rødplettet Blåfugl) one has to look for the black spot with white ring to be found in the cell of the basal field, which agestis does not have. However, there exists a form of icarus called icarinus that doesn't show that spot, why it can be necessary to look for other field marks. NOTE: The literature that I use to learn from indicate that this form is rare, but I've come across it several times on Amager, and with my, still, limited experience, third season, my personal experience would cause me to conclude that it is not as rare as indicated.
Males are blue above with a narrow black marginal band, with the outer margin bright white. The ribbons above are pale bluish.
The female above is darker, brownish with a bluish body and a blue suffusion radiating out from there. And it shows a row of orange spots running submarginally along both wings.
The underside pattern is similar on both sexes, but the ground color is darker brownish-beige on the female (a general trait of the blue butterflies). Characteristic for icarus is the white wedge that runs midwing from inside the orange spots to the row of black spots proximally.
To separate icarus from agestis (Rødplettet Blåfugl) one has to look for the black spot with white ring to be found in the cell of the basal field, which agestis does not have. However, there exists a form of icarus called icarinus that doesn't show that spot, why it can be necessary to look for other field marks. NOTE: The literature that I use to learn from indicate that this form is rare, but I've come across it several times on Amager, and with my, still, limited experience, third season, my personal experience would cause me to conclude that it is not as rare as indicated.
Similar species:
Life stages:
Distribution:
Europe, North Africa, the Canary Islands, and east across the Palearctic to Northern China
Habitat:
A variety of dry open fields; flower and grassy meadows, sandy heaths, overgrown abandoned sites, etc.
Behavior:
Moves short distances seeking flowers, but can be rather impatient constantly moving along, sometimes making it at challenge to approach well for good photos.
Gathers in small flocks in the afternoon to night-roost together on grass straws.
Gathers in small flocks in the afternoon to night-roost together on grass straws.
Status:
Very common in Denmark and the rest of the Nordic region.
The most common Lycaenidae in Denmark.
The most common Lycaenidae in Denmark.
Host plants:
Several plants of the pea family; especially Almindelig Kællingetand (Lotus corniculatus) [Bird's-foot Trefoil ~ Loto Corniculado ~ Käringtand]
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1168
(2 photos)
2022-07-18 Kalvebod Fælled, Denmark Imago ♂♀ Mating. The male above in the first photo, has switched to be underneath in number two. |
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1167
(1 photos)
2022-07-21 Kalvebod Fælled, Denmark Imago ♂♀ Mating. Not so big a color difference to the undersides. However, the female normally being the darker one, is the lower one. |
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1565
(4 photos)
2023-06-07 Östergötland Län, Sweden Imago ♂♀ Small meadow a few kilometers north of Yxnerum. |
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424
(3 photos)
2020-07-20 Kalvebod Fælled, Denmark ♂ Classic. |
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421
(3 photos)
2020-08-08 Kalvebod Fælled, Denmark ♂ Another colorless underwing that at first made me all excited, hoping that I finally found a different blue on the island. |
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417
(3 photos)
2020-08-08 Kalvebod Fælled, Denmark ♂ Worn, why the underside is very faded and probably why the body is lacking hairs. The faded appearance could be why the species-diagnostic black spot in the Cell, underside hindwing, is absent, rather than the animal being of a true variant. |
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419
(1 photos)
2020-08-08 Kalvebod Fælled, Denmark ♂ Weakly marked individual, as many have been lately. The Cell spot on the forewing is barely visible and no orange spots at all. Speculating if the little rain we've had during the summer and now a high pressure which has brought 30 degrees C to Denmark, continuing a week at least, has had any influence on the health of the population on Amager, making them weaker than usual? |
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495
(1 photos)
2021-05-29 Amager Fælled, Denmark Imago ♂ Another individual without the spot proximally in the cell of the forewing underside. |
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681
(2 photos)
2022-05-23 Kongelunden, Denmark Imago ♂ Good numbers early, following the general pattern this year. |
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1157
(5 photos)
2022-06-21 Kalvebod Fælled, Denmark Imago ♂ Ehv sporet. Was flying with normal looking individuals, but stood out with the almost turquoise tone above and certainly by the faintly colored underside. The forewing cell spot is barely visible. |
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1171
(2 photos)
2022-07-18 Kalvebod Fælled, Denmark Imago ♂ On Red Clover. |
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1170
(1 photos)
2022-07-21 Kalvebod Fælled, Denmark Imago ♂ Away from its normal habitat, on the handlebar of my bike. |
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1652
(1 photos)
2023-05-18 Bøtø-skoven, Denmark Imago ♂ One of the first this year. |
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1566
(1 photos)
2023-06-07 Östergötland Län, Sweden Imago ♂ Small meadow a few kilometers north of Yxnerum. A small batch of blues gathering for the night. |
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418
(3 photos)
2020-08-08 Kalvebod Fælled, Denmark ♀ Extremely worn, showing almost no traces of markings on the underwing. Fair to id it as this, simply because it is the only expected blue in the area. |
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422
(1 photos)
2020-08-08 Kalvebod Fælled, Denmark ♀ Fresh and typical. As much of it you can see. Perhaps the same as 423. |
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420
(2 photos)
2020-08-08 Kalvebod Fælled, Denmark ♀ Looks like a piece of both forewings is missing in symmetrical positions making me wonder if it has been attacked by something, taking a bite..? |
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423
(1 photos)
2020-08-08 Kalvebod Fælled, Denmark ♀ Perhaps this one is the same as 422. Freshly looking individual. |
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416
(3 photos)
2020-08-08 Kalvebod Fælled, Denmark ♀ |
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501
(1 photos)
2021-06-08 Kalvebod Fælled, Denmark Imago ♀ A worn example. It looks like the females at this time of year are very small and very dark on Amager. Not something you can see here, but I've noticed it when driving around. Most individuals are seen along the dike in the scarce and short vegetation. |
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683
(2 photos)
2022-05-23 Kongelunden, Denmark Imago ♀ Dark individual - perhaps they all are, of this first generation? |
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682
(2 photos)
2022-05-23 Kongelunden, Denmark Imago ♀ |
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1166
(1 photos)
2022-07-18 Kalvebod Fælled, Denmark Imago ♀ |
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1164
(2 photos)
2022-07-18 Kalvebod Fælled, Denmark Imago ♀ |
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1169
(2 photos)
2022-07-24 Kalvebod Fælled, Denmark Imago ♀ |
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1165
(1 photos)
2022-07-24 Kalvebod Fælled, Denmark Imago ♀ Worn |
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1563
(1 photos)
2023-06-07 Östergötland Län, Sweden Imago ♀ Small meadow a few kilometers north of Yxnerum. |
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1567
(2 photos)
2023-06-07 Östergötland Län, Sweden Imago ♀ Small meadow a few kilometers north of Yxnerum. |
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2078
(2 photos)
2023-07-28 Addit Hede (midtjylland), Denmark Imago ♀ |
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485
(3 photos)
2021-05-28 Kalvebod Fælled, Denmark Ellevehøj-sporet. A few early animals flying around. Here a male without the spot proximally in the cell of the underside of the forewing. Interesting to see the underside shining through in picture 1. |
Late in the season some animals can be very small and dark, almost causing the inexperienced observer to suspect a minimus (Dværgblåfugl).