Chalkie's picture

Brown Argus or Common Blue?

Observed: 5th May 2011 By: ChalkieChalkie’s reputation in InvertebratesChalkie’s reputation in InvertebratesChalkie’s reputation in Invertebrates
5.5.11 017 butterfly

Didn't settle for long - unfortunately the only time I managed to get a photo of one, it settled on some rubbish. There were a number of these flying around this lovely patch of grassland - at a petrol station. It appeared to be being looked after for wildlife, as the cowslips had been left to flower. There was a lot of ground ivy flowering too.
Is this a female common blue (or perhaps a brown argus?)

Species interactions

No interactions present.

Species with which Brown Argus (Aricia agestis) interacts


jonmortin's picture

It could be a Brown Argus or

It could be a Brown Argus or a Common Blue, I'm not sure. But by putting in a ? in the names, it will not bring up the photos of that species, or the NBN map etc. The "it might be this" option serves as a ? really!

Chalkie's picture

Dark marks...

The photo of the female common blue in my book also has a dark mark though (Complete Guide to British Butterflies - Brooks and Knight).

Michael Skelton's picture

Brown Argus

Although it is rather worn,I think there is a trace of chequering in the fringes. Also the complete absence of blue scaling makes me go for Brown Argus. Do you remember if there were small Cranesbills present?

Chalkie's picture


There were some small cranesbill leaves - but none flowering, so I didn't try identifying them any further than that. But the more I've looked at photos of both brown argus and common blue, it looks more argus-like to me. Although there's a blue-ness about the body, I don't think the wings are any bluer than the photos I've found of brown argus (eg on uk-butterflies site).

I've not (knowingly) seen Brown Argus before, so I'd quite like it to be that...

A pity I didn't get any more photos, as there were quite a few butterflies there, and one of the others might have been less tatty (or, of course, could have been a different species). Maybe I will never know! Fun trying to find out anyway, and I've got a much better idea of what to look for next time.

jccurd's picture

Chequered Edge

I also think Common Blue for two reasons:

1. The "furry body" is clearly tinged blue;
2. My book shows the Brown Argus to have a more chequered Edge to the wings - this is clearly plain.

Awkward, no? All organisms should have bar codes but that would be no fun. :)

Martin Harvey's picture


Tricky, but the length of the abdomen compared to the hind wings seems to me to indicate that this is a male Brown Argus, rather than a female Common Blue (in which the abdomen is shorter than the wings), and the bright orange spots seem a better match for Brown Argus as well.

Brown Argus doesn't have blue scales on the wings but can have blue iridescence around the wing base and thorax. Common Blue females nearly always have at least a few blue scales on the wing itself.

Entomologist and biological recorder

jccurd's picture

Good debates ...

... can usually be guaranteed by a couple of old faithfuls:

1. Brown Argus v. female Common Blue;
2. Chiffchaff v. Willow Warbler.

It certainly beats TV. :)

Chalkie's picture

Definitely beats TV! Give me minibeasts and flowers any day.

And I'd only identify a chiffchaff if it chiffed and chaffed - this year is the first time I've ever actually seen one (heard them loads of times before though), and it was very obliging. I've never seen a willow warbler yet. As far as I know.