Penny caught up with this pristine Chalk Hill Blue at Perryfields Quarry on Portland on 2/08/18.
The Chalk Hill Blue is found on chalk downland, although limestone downland is also used. it can be found from mid July – early Sept, and in flight looks a lot lighter than other Blues. The chequered border to the wings is a good way to distinguish it from Common Blue when at rest.
Whilst visiting Fontmell Down on 3/08/18 Mark came across this Chalkhill Blue, aberration. He tells us he feels sure he saw a similar one there a couple of years ago. There are many aberrations of various species of butterflies and more information can be found on this link. http://www.ukbutterflies.co.uk/aberrations.php
James tells us he spent a lovely morning at Tout Quarry on 17/07/18 where he photographed these Chalkhill Blues.
The top photo is of a female and the above photo shows the markings of the undersides clearly for ID purposes. Common Blues have very similar underside markings, but the diagnostic markings are those around the rim of the wings, There is a chequered effect on Chalkhill Blues and a plain white rim on Common Blues.
Penny photographed this beautiful male Chalkhill Blue at Kingbarrow Quarry, on Portland on 25/07/17.
The caterpillar foodplant of this species is Horse-shoe Vetch, and the adult butterfly can be seen on the wing from late June to early October. It prefers dry flowery places with short grass, usually on limestone, but always alkaline soils.
Mark took this photograph on 13/07/17 at Badbury Rings not realising at first that it showed extra markings.
You can see there are small silver studs on this butterfly’s underwing, similar to those of the Silver-studded Blue. We have had a suggestion this is a variation called argenteogutta, which seems to translate as ‘silver drops’. The Chalkhill is well known for its aberrations – there was an entire book on them published in 1938.”
Chalkhill Blues can be seen on the wing from late June-early Oct depending on locality and altitude, but are becoming increasingly rare in England.
Andrew photographed this stunning butterfly at Portland at the end of July. The blue shade of the male ups (fore-wing and hind-wing upperside) is regionally variable but in the UK is usually as seen here.
Mark saw this lovely speicimen at Badbury Rings on 13/07/207, which he notes is the earliest he has seen this species there.
We have concerns about the future of the Chalkhill Blue in Dorset; it flourishes on Portland, but is declining elsewhere: a drop of 40% over the last five years is recorded on out Butterfly Distribution Atlas page.
Mel says: “Pleased to see quite a few Chalkhill Blues at Badbury Rings this morning [25 July]- and also a Common Blue that seemed to be involved in endless arguments with its Chalkhill cousins! Attached shot is of the first Chalkhill I spotted.” And a superb shot it is too.