Queen of Spain fritillary (Issoria lathonia)
The Queen of Spain fritillary is a fairly common butterfly in Europe and temperate Asia, but it only occurs in Britain as an extremely rare migrant, in fact there have been less than 400 records of this species since it was first recorded 300 years ago by William Vernon at Gamlingay, Cambridgeshire. The biggest migration was in 1872 when 50 were recorded in Britain, and in 1945, no less than 25 adults were recorded from Portreath in Cornwall, indicating that the butterfly had successfully bred there. However there have been many years when not even a single specimen has been recorded anywhere in Britain, although there are possible indications that migrations may be increasing, most likely as a result of climate changes increasing the butterfly's abundance in northern France.
An unusually high number of adults were recorded in 2007, when 6 were reported from various parts of Hampshire and Sussex. These migrations seem to originate from Normandy, and funnel into the UK via river valleys. Small migrations also took place in 2008 & 2009. In the latter case a single female arriving in West Sussex in July produced offspring which emerged in September and October - at least 7 different adults were recorded, including a mating pair on October 13th.
The very distinctive large silver spots on the underside hindwings mean that this butterfly is unlikely to be confused with any other species, although early summer specimens could possibly be mistaken in flight for a pearl-bordered or small pearl-bordered fritillary. In late summer or early autumn they could be confused in flight with a wall brown but the differences are obvious as soon as the butterfly settles.
Both sexes are very similar in appearance, although the female is slightly larger, with a shorter abdomen and a more greenish hue around the base of the upperside wings. The sexes can more easily be distinguished by their behaviour - females are sedentary, while males actively pursue all passing butterflies.