www.ukbutterflies.co.uk

I've been encouraged to join this forum and browse the pictures here to check out my suggestion of a way of distinguishing between the females of Adonis Blue and Chalkhill Blue.

It seems to me that the Adonis Blue has about 20 or 21 white rings on each antenna, whereas for the Chalkhill Blue the count is 24 or 25.
Admittedly they do get difficult to count at each end! The white rings do seem more prominent with the Adonis.

The pictures I've browsed in the gallery here, do seem to support this observed difference.

Has anyone else noticed this? Any comments?

Mike Kerry
(acclivity)

That's a fascinating hypothesis. I for one havent read that anywhere before.

Good observation. My photo collection show an even greater difference. CHB 26/27, Adonis 17/18 both females and males.

Can't find a good enough photo of hybrid polonus to check that.

Jack

Thank you bugboy and Jack

I think you have made an excellent observation, acclivity. I have been browsing my own catalogue of photos over the last few years and made the following selection. Many of these photos are of mating pairs, which helps confirm the ID.
Although the number of white rings is variable in both cases, there are always fewer in Adonis and the white rings appear more widely spaced in the central part of the antennae.

Now to look at some males as well!

Mike

Mike Kerry seems to have stumbled on something very useful as a method of distinguishing similar species.
So is anyone up to trying this hypothesis on similar Continental blue species? Or closer to home, such as Essex and Small Skippers?
(My own photos aren't good enough)

Jack