Sloe Hairstreak (Satyrium acaciae)

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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.

16239_male_Var_18Jun09 10743_male_Var_23May08 30063_male_Var_30Jun12
35346_male_Var_9Jun14 40784_male_Alpes-Maritimes_25Jun16 40951_female_Drôme_4Jul16

This is one of a family of very similar hairstreaks of the Satyrium genus, including the Ilex (S. ilicis), the False Ilex (S. esculi), the White-letter (S. w-album), the Black (S. pruni) and the less-similar Blue-spot Hairstreak (S. spini). Acaciae has larger and rounder red spots on the unh with internal black triangles on the margin and black edging externally. The post-discal white line is also (usually) quite strong and almost straight (c.f. ilicis and w-album). Although it looks superficially similar to the other Satyrium species, with a clear view it can be identified with some confidence. It often flies in company with its Satyrium cousins, but can often be identified by its (usually) smaller size and rather rounder shape.

 

Prior to 2004 I had only seen it in one locality in the Alpes-Maritimes, but since I have seen it in a number of different localities, mostly at mid-altitude, but usually not more than a few in any locality. In 2006 I found it in large numbers in Var from late May to late June with a peak emergence around the second week in June when it was out in good numbers, flying in company with both ilicis, esculi, and spini.

The low-lying yellow flowers of the Helichrysum genus seemed to be a strongly favoured nectar source of all the Satyrium species, often with several hairstreaks on each flowerhead. Sometimes the Satyrium hairstreaks could be counted in hundreds and maybe thousands.

 

The sexes are similar, but it appears that the female has a more prominent post-discal line, stronger lunules and markings and slightly longer tails. The tip of the female abdomen, where visible, is black. Thus 16239 and 10743 are clearly males, while 40951 illustrates the difference very clearly.

 

 
ref sex

observations

alt. m
16239 M

a male, for the same reasons as 10743.

780
10743 M

a male, I suspect, based on the tip of the abdomen is just visible and does not appear to be black. 

185
30063 M a male, perhaps, as just enough of the tip of the abdomen an be seen and maybe the black tip would be apparent. 680
35346 M a male. 220
40784 M a rather greyish male 1000
40951 F a female, as indicated by the clearly-visible black tip at the end of the abdomen. 1220

 

16239_male_Var_18Jun09

 

10743_male_Var_23May08

 

30063_male_Var_30Jun12

 

35346_male_Var_9Jun14

 

40784_male_Alpes-Maritimes_25Jun16

 

40951_female_Drôme_4Jul16