LEPIDOPTERA (Butterflies & Moths) > PAPILIONOIDEA (Butterflies) > Lycaenidae > Polyommatinae

I'm sure that most seasoned butterfly enthusiasts know their 'blues' well enough that they rarely need to resort to field guides in order to check details the way that I do. Although I know most of the defining features, I still have to compare photos, particularly when the individual in question is resting with closed wings.

Apart from the rare Large Blue, I'm fortunate that the remaining seven British species all occur within a short drive from home. I photographed five during my first year and will now be looking for the other two; Small Blue [Cupido minimus] and Silver-studded Blue [Plebeius argus].

The first 'blue' I photographed was a Holly Blue [Celastrina argiolus], which visited our garden during the pandemic 'lockdown' in 2020. Until then I assumed that all butterflies were much the same size, but of course this species, like many others, is about half the size of a Red Admiral or Peacock. It took me a while to ascertain that it was a Holly Blue and not a Small Blue, which is when I started to appreciate that habitat and time of year often provide good clues to the identification of many species.

The Common Blue [Polyommatus icarus] is the most widespread species and one that can occur in a variety of habitats from May through to September. The upperside of the male's wings are blue with a fine black border and plain white fringe, whereas the females are darker, more of a blue-brown, edged with orange spots. They are less frequently seen as, unlike the males, they tend to keep themselves hidden away.

My favourite local chalk grassland site at Martin Down is home to a number of butterflies and a location where I can be pretty sure I'll see the Chalkhill Blue [Polyommatus coridon] during July and August, and with a bit of luck, a little earlier or a little later, the double-brooded Adonis Blue [Polyommatus bellargus]. The females can easily be confused, which is why I always carefully check wing margin and/or underwing spotting details against similar photos with confirmed id's. Fortunately, the males are more straightforward as long as you can see the upperside of the wings; the Chalkhill being a pale, almost silvery blue, and the Adonis with its beautiful, albeit variable, bright sky-blue colour. Both species have a 'near threatened' conservation status.

The final 'blue' is the Brown Argus [Aricia agestis], which you'd expect to be with the 'browns' until you realise that it superficially resembles the female Common Blue and, although it can pretty easily be identified when basking with its wings open, is actually a little bit trickier with its wings closed. With the exception of the Small Blue and Holly Blue, all these species have similar spotted underwings. Thankfully the Brown Argus has distinctive double offset spots on the hindwing coupled with a single, rather than double, forewing spot - difficult to envisage, but reasonably clear when viewed. Although I've photographed this species at a few different locations, my best encounters have been at Martin Down.