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Small Blue

Photograph by: 
Peter Orchard

The smallest British butterfly favouring small patches of kidney vetch. Very limited in range.


  • Small Blue: hide and seek

    Post date: Wednesday, 20 May, 2015 - 00:00

    The small blue (Cupido minimus) is certainly a small butterfly; indeed it is the smallest British butterfly with each wing is little more than 1/4 inch across so my photo may be a little misleading. Whilst it is small it is not blue however! This is the male which has just a hint of blue on a charcoal background whereas the female lacks the hint of blue altogether. It has no other markings on the upper side of the wing but does have the light coloured border like most of the other members of the family. 

    Small blues are hard to find for a variety of reasons. Firstly, their size means they are easily over looked. Then they have a very short season flying for a couple of weeks around the end of May and beginning of June although there is a partial second brood here in the south towards the end of August. Thirdly, they are quite rare, found in very few locations and in Dorset we have small colonies at Durlston and on Portland; there maybe elsewhere but I am not aware of any. Finally, they live in little pockets just a few yards across; they favour small patches of kidney vetch. It is possible to be in the right place at the right time and yet miss them because they are so limited in range. 

    Going looking for the small blue? The very best of luck!


  • Small Blue in Dorset: what your tweets tell us ...

    Post date: Tuesday, 23 April, 2019 - 21:13

    The small blue is certainly small, it is the smallest of our British butterflies, but it is not blue; both sexes are brown with the male being a darker, bluish brown. Although somewhat plain I think they are a delicate and quite attractive little insect. They have a preference for calcareous grasslands where kidney vetch and horseshoe vetch are present; the female lays her eggs only on kidney vetch. The males spend a lot of time resting on bushy vegetation ready to ward off other males whilst waiting patiently for a female to come within range. Because of their lack of activity and their small size they can be easily overlooked but, in any case, they are not a common species although they seem to be doing quite well in Dorset.

    Small blue fly from mid May until the end of June and then often have a second brood in late July and August. The reports for 2017 and 2018 from Dorset tweeters surprisingly shows two records for week 16 at the end of April with records starting in earnest in week 19, mid May, in line with the text books. There are then records for every week until week 22 in mid-June and then just one in week 28 at the end of July which will be a second brood adult. There are currently only 19 reports for the two years combined so it is difficult to draw too many conclusions.

    There are records, which include some from other survey data, from twenty four sites in Dorset which does demonstrate that it is doing well here. Portland and the Purbeck coast are good for them but the real bonus is a strong colony establishing itself along the new Weymouth relief road that was built for the 2012 Olympics; kidney vetch now occurs along this road's embankments in abundance and it seems small blue have responded well to that. Other sites occur along the chalk spine that runs from the Bridport area north-eastwards towards the Wiltshire border near Cashmoor.


Common Name Small Blue
Scientific Name Cupido minimus
Species Group Lycaenid Butterflies Blues and Hairstreaks
Interest Level
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Identification Notes
Primary Habitat
Preferred Environment
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Additional Identification Notes
Similar Species

The records for this species have been organised into reports, charts, maps and photos. Click a pic below to see the detail:

Notebook Sites List Distribution Map Some Charts Some Photographs Recent Records Guidance Notes

To see related species click here: 

Lycaenid Butterflies Blues and Hairstreaks