Sussex Butterfly Conservation : Species

Butterfly Species in Sussex

A territorial male Small Blue – photo by Martin Kalaher

Small Blue

Cupido minimus

Description

This lovely blue butterfly is our smallest UK species, and in Sussex it may be found all along the South Downs, but more particularly the downland between Eastbourne and Amberley. It becomes increasingly difficult to find on the more-wooded downland to the west of the River Arun. Most colonies are small, with fewer than 30 adults at their peak, and many colonies are smaller still, and given the butterfly’s tiny size, it is very easily overlooked.

In flight it is quite easy to confuse a Small Blue with a very small Brown Argus. Often our first inkling that it is present, is when we inadvertently disturb the butterfly, and then we must try and follow its rapid flight, see where it perches, and then take a closer look.

A male Small Blue uses a prominent perch within its territory and waits patiently for a female to come to him. If we manage to spot one, and then approach very slowly, it is likely to remain where it is, and with luck we will have a close-up view, and a great opportunity to take a photograph or two. It is a beautiful butterfly, with uppersides that are a uniform charcoal-grey. The male has a variable amount of dusting of blue scales (which is given the delightful name of “fairy dust”) and whilst the background colour of a female is very similar, she does not have any blue scales.

Between 2006-2024 the “average first sighting” was May 10th (range, April 28th to May 16th) and this first brood continues until early July. There is a small second generation which begins in mid-July and ends in mid-September. A very occasional third brood is recognised by some lepidopterists, and these may be present in late September/October. A particularly late individual was recorded by Dave Harris, near Meeching Quarry nr Newhaven, on 18/10/2003. For the years 2006-2024 the “average last sighting” was August 16th (range, July 26th to September 12th).

Kidney Vetch is the principal larval foodplant of Small Blues. It is an interesting plant of chalk turf, readily colonising any bare patch of soil, but within a few short years it can often disappear. It doesn’t compete well with other plants, especially grasses. This characteristic of Kidney Vetch means that Small Blue colonies can come and go quite quickly, the butterflies moving on to the next “new patch” of their foodplant. Despite its tiny size it is powerful in flight and appears to have no difficulty in flying a few miles and colonising a new area.

Where to find

More-or-less anywhere on the South Downs where we can find Kidney Vetch. Some of the larger colonies can be found at Castle Hill NNR from TQ369071 to TQ366069, Friston Forest Gallops from TV544991 to TV554997, Kithurst Hill at TQ070125, Well Bottom at TQ4505 and Windover Hill from TQ532032 to TQ543033.