There are only a few species of butterfly that we see in early spring and generally the earliest individuals seen each year are those that survive the winter by hibernating in their adult form. One butterfly which regularly over-winters in Britain is the small tortoiseshell.
When it looks for a safe place to hibernate, the small tortoiseshell will often hide away in an outhouse or shed, so our gardens offer great refuges for them through the winter. Upon emerging in spring, their priority is to find nectar so a well-stocked flower garden is their saviour again.
Growing flowers in our gardens is one thing but it takes a really environmentally-conscious gardener to provide the small tortoiseshell with its most desired plant, the stinging nettle which is the food-plant of its caterpillars. If you choose to grow nettles in your garden to support butterflies then a sunny spot is best.
So strong is the association with nettles that the butterfly’s scientific name, Aglais urticae, is partly derived from urtica meaning stinging nettle. Aglaia was one of the three Graces, a daughter of Zeus admired for her beauty, and the choice of this name reflects the elegance of the small tortoiseshell.
In return for providing a garden full of nectar-rich flowers, on which these butterflies can feed, we get the opportunity to watch one of Britain's most colourful and attractive butterflies. The adult small tortoiseshell is approximately two inches across and has beautiful orange, yellow and black markings on its upper wing, bordered by blue spots. The lower wing is dark brown and serves as camouflage while the butterfly is asleep.
The small tortoiseshell is widespread over the whole of the UK and it has two broods every year, the first brood of eggs is laid in May by adults which have hibernated through the winter. Adults from this first batch of eggs begin flying during July and their eggs ensure a second population of adult butterflies in late summer. It is only the adults from this second brood which will hibernate over winter.
In recent years there has been a decline in the number of small tortoiseshell butterflies and at the moment scientists are still unsure as to the exact cause. One suggestion is that a parasitic fly, prevalent on the continent, is attacking the larvae of the small tortoiseshell, this theory ties in with the fact that its decline has been most noticeable in the southern half of the UK.