There are 56 British butterflies species breeding in the UK. These are represented by just six families, skippers (Hesperiidae): swallowtails (Papilionidae): whites and yellows (Pieridae): hairstreaks, coppers and blues (Lycaenidae): metalmarks (Riodinidae) and the fritillaries, nymphalids and browns (Nymphalidae)
Two of these families are represented by only one species, the Papilionidae by the swallowtail (Papilio machaon), which is confined to Norfolk Broads and the Riodinidae by the Duke of Burgundy (Hamearis lucina) found only in local areas in the north-east, north-west and south-east England.
Twenty nine of Great Britain’s breeding butterfly species are listed as ‘High UK priority’, with 9 of those regarded as requiring ‘urgent action across their UK range’. Butterfly Conservation found further evidence of the serious, long-term and ongoing decline of UK butterflies, with 70% of species declining in occurrence since 1976. and overall, 76% of the UK’s resident and regular migrant butterfly species declined in either abundance or occurrence (or both) over the past four decades. By comparison, 47% of species increased in one or both measures. This is of great concern not just for butterflies but for other wildlife species and the overall state of the environment.
Being able to tell the difference between male and female butterflies is dependant on the species. Some species such as the painted lady butterfly look the same in color and markings and can only be differentiated by examining anatomical structures. Males tend to have a more slender abdomen and females tend to have larger rounded abdomens. Some species can be identified by differences in the shape of the forewings. Hairstreaks are a good example of this, males have triangular forewings and females’ forewings have a more rounded shape.
Subtle wing pattern differences are apparent in the monarch. Males have a round black dot in the hindwing that the females do not have. The Gatekeeper, also known as the Hedge Brown, are more easy to tell apart — only the male has the distinctive sex brands on the forewings. On the other hand female common blue butterflies varies from almost completely brown in southern England to predominantly blue in Scotland
Another common difficulty is with the female adonis blue which is easily mistaken for a female chalk hill blue and the two species occasionally fly together toward the second half of August on some sites. Distinguishing the two is not at all easy.