Common Blue Female vs Brown Argus

[eccles]

At my local patch today were common blue and brown argus. A butterfly was smaller than average for a blue and looked brown. After taking several photos I conclusively identified it as a female blue.
Look at the shot below, at the inner row of black dots on the underwings. There is a row of four on the hindwing, extend into the forewing with an additional two dots.
Also, note the scattering of blue scales on the upper forewing.



Now look at a couple of shots of another individual. In this case there are no blue scales on the forewing at all, and on the underside there is the row of black dots on the rear wing, just three in this case, but none at all in the corresponding position on the forewing. This is a brown argus.

[Martin]

Thank's for that eccles...I just hope I can remember it. I've taken in so much information in the last couple of months since getting "into" b/flies my brain is turning to mush!

Martin.

[David Tipping]

Interesting, eccles - I don't think I've ever seen such a predominantly brown common blue as the one in your pic.
I think the moral of all this is that for positive identification you need either a good photograph or a photographic memory!