www.ukbutterflies.co.uk

Could someone help me with this one please. It was spotted on Whitmoor Common, Guildford. I think it's either a Chalkhill Blue or Adonis Blue.

Thanks
Paul

Hi Paul,

I think this is a female Chalkhill Blue.

It's a Chalkhill or Adonis Blue because the white fringe is cut by black bands.

And it's a female Chalkhill Blue because the colour between the red dots on the hindwing and the white fringe is brown & white, rather than blue. As explained here:

http://www.ukbutterflies.co.uk/species. ... nis%20Blue

Cheers,

- Pete

I'm not saying you're wrong, Pete as I'm new at the CB/AB identity game, but an adonis was very interested in this female last week, and there's not a blue scale to be seen. It's a rather worn specimen though.

Thanks for the replies. I wasn't expecting to see either a Chalkhill or an Adonis so this one threw me a bit!

Hi eccles,

I think your female is Chalkhill also

Cheers,

- Pete

This thread has been bugging me

Distinguishing the females of Adonis and Chalkhill Blue is pretty difficult. So I took a trip to Martin Down today and spent 3 hours looking solely for females of both species. I've come to the following conclusion:

1. Even close-up, it's sometimes difficult to see the blue scales on the female Adonis Blue, between the red hindwing markings and the white fringe.

2. The female Adonis Blue has a blue/purple sheen that is missing from the female Chalkhill Blue.

3. The condition of the individual is a real giveaway. I only found 1 female Chalkhill Blue and it was absolutely tatty. All female Adonis Blues were immaculate (I found 11 of them).

4. Adonis Blue females are a darn sight harder to find than female Chalkhill Blue. They're easily mistaken for Brown Argus, and spent more time in the shrubbery, and less on flowers, than female Chalkhill Blue.

2 pics of the same female Adonis Blue for your viewing pleasure - showing just how subtle the blue markings are!





Cheers,

- Pete

Interesting that the adonis male that I saw was giving the eye to the female that I posted! They didn't mate incidently, which is probably just as well as going by what you've added then it's pretty conclusive that my example was a chalkhill. Thanks for the additional explanation.

Chalkhill Blue and Adonis Blue have been known to interbreed (resulting in a hybrid called "polonus"), although (I believe) the offspring aren't viable (i.e. they produce infertile ova). A photo is at:

http://www.ibc.regione.emilia-romagna.i ... 650003.htm

Cheers,

- Pete

Interesting. They must be a recent species separation from a common ancestor. I wonder if that's why adonis isn't so common as chalkhill? Chalkhills have been around and laid eggs for the next generation by the time the second brood adonis gets going but if the male chalkhills are still going strong then they could displace the smaller adonis males.

Any tips on how to identify this? It's either a Chalkhill or an Adonis Blue, I think.

Simon C