Cupido (Everes) argiades

Male, Switzerland, August 2008

Male, Switzerland, August 2008

Male, Switzerland, August 2008

Male, Switzerland, August 2008

Male, Switzerland, August 2008

Male, Switzerland, August 2008

Female, laying on bird's foot trefoil, France, August 2008

Female, France, August 2008

Female, Switzerland, August 2008

Male, France, August 2008



Egg laid on clover, Switzerland, August 2015



The same egg

Distribution

The short-tailed blue is widespread in Europe but within its overall range its actual distribution is rather patchy. In my local region of Switzerland it has become very much commoner in recent years. Before 2008 I had never seen one in the country. In the summer of that year I discovered several concentrations in places I had previously looked in vain for them, and continued to find individuals in the same places the following spring. Over the next few years they moved into grassland and woodland right near where I lived and where I would certainly have seen them if they had been there before. For the last few years I have seen them regularly all over my local region. Anecdotally, I have heard similar stories of expansion elsewhere.

In western Europe, the only species this might be confused with is the Provençal short-tailed blue. The most obvious difference is the orange lunules towards the anal angle of the underside hindwing, which the Provençal short-tailed blue almost completely lacks. There may be a hint of orange in this latter species, though, and spring brood short-tailed may equally show very little. It is important to get a very good view in ambiguous cases. The tail is also stronger and longer in short-tailed - sometimes reduced to a mere kink in the margin of Provençal short-tailed - and the female short-tailed usually shows some blue on the upperside. There is never any blue at all on the female Provençal short-tailed. In Eastern Europe a third species flies, the eastern short-tailed blue, Cupido decoloratus. This is largely similar to the Provençal shor-tailed, like that species lacking any orange, and is also distinguished in the male at least by the presence of a dark, discoidal mark on the upperside of the forewing.

Short-tailed blues use a variety of food plants from the pea family. I have seen spring brood females lay on sainfoin and summer brood females at the same site lay on birds-foot trefoil. In my local Swiss meadow clovers are used. The first brood flies in April and May, producing a summer generation in late July or August, which may be seen on the wing into September. They overwinter as caterpillars.