Plebejus optilete

Cranberry Blue (Plebejus optilete)

2024 photographs highlighted in yellow. Click on any photograph to go to an enlarged picture, or simply scroll down the page.


31217_male_Valais, Switzerland_14Jul12	41798_male_Savoie_21Jul16	31263_female_Valais, Switzerland_15Jul12	45595_male_Savoie_12Jul18

41800_male_Savoie_21Jul16	23208_male_Valais, Switzerland_26Jul10	31223_male_Valais, Switzerland_14Jul12	48707_male_Savoie_23Jul21

31278_female_Valais, Switzerland_15Jul12	36260_female_Savoie_17Jul14

A rather uncommon (in France) blue of high altitudes which I saw for the first time in 2010. From the underside, it is easily identified by the single orange unh lunule in s2, although there is sometimes a smattering of orange scales in s1 and s3. The male upperside is a strong violet-blue while the female is black with a smattering of blue scales in the basal regions, creating a rather appealing effect. The undersides of both sexes seem to be identical from what I have seen.

In terms of size, it is typical for Plebejus species, perhaps slightly smaller than the Common Blue (Polyommatus icarus).

It is principally a species of north-eastern Europe and Fennoscandia, with its range extending to the Alpes. In France it occurs only in the high northern Alpes in Savoie, Haute-Savoie and Isère, and in a few localities in the Hautes-Alpes. In 2010 I searched for it in the Hautes-Alpes at 2200-2400m altitude without success.

I found it for the first time in 2010 in central Switzerland in small numbers clearly at the end of the flight period and then as often seems to happen, saw two more males at other separate locations in western Switzerland, but rather fresher. However, in one location in 2012 it was very common, the numbers being measured in hundreds, all males. On the next day, a rather overcast day with very little flying, a single female was seen on the ground (31263/31278). This is the only female I had seen until 2014 when 36260 was seen in Savoie.

This species used to be known, until recently, as Vacciniina optilete, and is still referred to as such in a number or works. The larval hostplant is Bog (or Northern) Bilberry (Vaccinium uliginosum) and optilete is closely tied to it.

In 2010 it was reclassified as Plebejus optilete and in 2017 it was again reclassified back to Agriades optilete. I'll give it a few years before changing the web page (and all the occurrences and links associated) as it is entirely possible that the taxonomists will change it again.

ref	sex	observations	alt. m
31217	M	*a male. The blue behind is an Idas Blue (P. idas).*	2020
41798	M	a male, taking salts. One of a number puddling together, and a clear deep blue that almost makes this species identifiable from the upperside view alone.	2090
31263	F	a typical female. 31278 is the underside.	2020
45595		a male, puddling. The unh markings are quite bold, even by the standards of this species, and the blue scales are very much in evidence.	2090
41800	M	a rather dusky underside, with unusually greyish unf post-discal spots. This is the underside of 41798 as may be apparent (apart from the sequence numbers) by the pollen adhering to its head.	2090
23208	M	a male underside, with the characteristic single strong orange lunule.	1570
31223	M	a beautifully marked male underside.	2020
41707	M	a male, taking salts from damp ground. The markings are a little muted compared to others on this page, especially on the forewing where they look a little out of focus (but I don't think are).	2090
31278	F	a female underside (31263 is the upperside), being almost identical to the male upperside.	2020
36260	F	*a female, a rather duller example, seen in a boggy area of Savoie at lower altitude than usual for this species. As usual, the larval hostplant V. uliginosum* was in the vicinity.**	1560