Common Blue (Polyommatus icarus)

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2016 photographs highlighted in green. Click on any photograph to go to an enlarged picture, or simply scroll down the page.

14655_male_Var_21Apr09 31771_male_Var_21Apr13 34490_male_Var_19Apr14
35265_female_Var_6Jun14 33060_female_Alpes-Maritimes_28Jun13 14921_female_Var_06May09
10707_female_Var_22May08 13682_male_Gard_22Aug08 16867_male_Alpes-Maritimes_27Jun09
17004_male_Var_30Jun09 37196_male_Alpes-de-Haute-Provence_11May15 19853_female_Var_3May10
14874_female_Var_05May09 14917_female_Var_06May09 24675_female_Var_09May11

A very common and very widespread blue, probably the most common in Europe. It is quite variable and, from the underside alone, could easily be confused with several of its Polyommatus cousins. The male upperside is fairly constant, although worn specimens can appear darker blue in flight. The male upperside black marginal line is usually thinner than the Chapman's Blue (P. thersites) and other differences are outlined on the thersites page.

 

Females can vary greatly with regard to the amount of upperside blue scaling, varying from brown with almost no blue, to extensive blue, with almost anything in between. The female underside, being brown, is very similar to the Brown Argus (Aricia agestis), the constant key being that the top three of the unh post-discal spots that make a right-angle (or maybe more of a curve) are in line and evenly spaced in icarus, but in agestis the second spot is closer to the first and displaced downward - see below (icarus on the left, agestis on the right). 

Also agestis does not have a unf cell spot whereas icarus does, but enough of the unf has to be visible in order to be sure that there is no cell spot (in agestis) - this is visible in the small photographs below.

 

The underside can vary considerably with respect to the ground colour, where the male is usually grey but can the unh can sometimes be pale brown, and the orange lunules can vary greatly in terms of colour, and may be rounded or pointed. It's usually a case of eliminating other species, rather than positively identifying icarus from the underside alone. The Eros Blue (P. eros) has a very similar underside, but eros is confined to the higher reaches of the Alpes and Pyrénées.

 
ref sex

observations

alt. m
14655 M

it may be common, but a fresh male still has a beautiful bright blue upperside.

140
32771 M a male, the wings showing the underside markings, although not because the photograph is backlit. 140
34490 M a male, bright blue but not as bright as the Adonis Blue (Polyommatus bellargus). 20
35265 F a female. 20
33060 F a female, with the uph almost completely blue and the upf mostly brown. 1000
14921 F

a female, almost completely brown with only faint blue scaling in the uph marginal region, and strong lunules extending to s3 on the upf and a weaker lunule in s4.

220
10707 F

this female is of the blue form, with extensive blue uph scaling but the full-ish set of unf lunules indicates icarus. It could be confused, from the upperside alone in early season, with the female of the first brood thersites (the second brood female is the more normal plain brown). The key differentiator (as it appears to me) seems to be that the upf orange lunules extend to the costa in icarus but only to about s3 or s4 in thersites.

340
13682 M

a male, with pale brown unh ground colour and strong elongated red lunules.

70
16867 M

a male with nice clean underside markings and strong bright orange lunules.

900
17004 M

a male with a slightly darker unh ground colour and rather weak and rounded black chevrons lining the orange lunules.

920
37196 M a very typical male, with a rather greyer, cleaner ground colour than most on this page. 560
19853 F

a female, with very strong and contrasted markings, and a degree of aberration in the unf discal spots.

140
14874 F

a female with very strong and pointed orange lunules and black chevrons, normally more indicative of the female Escher's Blue (P. escheri) than icarus.

140
14917 F

a female, by contrast with very weak unh marginal lunules and markings generally.

220
24675 F a quite dark and heavily marked female. 220

 

14655_male_Var_21Apr09

 

31771_male_Var_21Apr13

 

34490_male_Var_19Apr14

 

35265_female_Var_6Jun14

 

33060_female_Alpes-Maritimes_28Jun13

 

14921_female_Var_06May09

 

10707_female_Var_22May08

 

13682_male_Gard_22Aug08

 

16867_male_Alpes-Maritimes_27Jun09

 

17004_male_Var_30Jun09

 

37196_male_Alpes-de-Haute-Provence_11May15

 

19853_female_Var_3May10

 

14874_female_Var_05May09

 

14917_female_Var_06May09

 

24675_female_Var_09May11