Posted 5th Jun 2014
With over 50 native species calling Britain home, we are host to a rich population of striking and unusual butterflies that thrive at this time of year
What could be a more beautiful sight in summer than butterflies clustered on a spike of buddleia or fluttering around a lavender bush? Their colourful wings and gentle flight never fail to lift our spirits as they bask in the warm summer sunshine.
In July and August most butterflies have emerged from their pupa and can be seen at their most active on the wing or feeding from the nectar of flowering plants. For many species it is now time to find a mate and lay eggs on or near caterpillar food plants before they reach the end of their life. The fascinating four-stage butterfly lifecycle takes about a year to complete, but with considerable variation in the timing of each stage between different species.
In Britain there are 59 native butterfly species living in areas as diverse as woodland, mountains, marshes and sand dunes. A further three species are regular summer visitors and other species may migrate to Britain if conditions are favourable enough. The habitat of each butterfly is controlled to a large extent by the availability of food plants for both the larvae and the adult butterflies. Butterflies are a reliable indicator of the health of our delicately balanced ecosystem, so the more we see of them, the better. Each stage of their relatively brief lives is governed by changes in temperature, humidity and flora, with most preferring warm, sunny conditions after plentiful rainfall has provided their preferred leaves and nectar.
Sadly, British butterflies have been declining for many years, dramatically so in recent times with almost three quarters of UK butterfly species decreasing in population during the last decade. Of the 19 species considered to be threatened, eight are endangered and two - the high brown fritillary and the large blue - are critically endangered. Unfortunately, human activity is the biggest threat to these delicate creatures. Changes in the management of farmland, woodland and open spaces, coupled with the demand for new buildings on previously green sites have had a significant impact on butterfly habitats. The use of chemicals in farming has also affected the availability of flowering plants which provide food for all insects, and common wildflowers - often recognised as weeds - are not always popular with gardeners.
The ever-changing British weather is another major factor in the decline of the butterfly. Several wet summers have occurred in the last 10 years and it isn't just us who are unhappy. The poor conditions have significantly reduced the butterfly population which requires warm sunshine. Rain can not only injure a butterfly, but the absence of sunlight causes a drop in temperature that can reduce their ability to fly. Thankfully, the warm summer last year provided ideal conditions for butterflies and numbers of almost every British butterfly species in the UK increased again.
Identifying the plethora of British butterflies we have can be tricky, particularly when theyare flitting from plant to plant. The pretty peacock butterfly (pictured right) is one of our most striking species, found throughout the British Isles, with unmistakable eyespots on its russet wings, it's often seen feeding on buddleia. The small tortoiseshell with its beautiful blue beading around orange and black chequered wings is another easily recognisable species, though one sadly in decline. Both butterflies spend most of their life at the butterfly stage, feeding on the nectar of common wild plants such as thistle, dandelion and bramble, hibernating during the winter months in a sheltered spot such as a shed or woodpile. They awake at the first sign of warm weather, usually March or April, when the male seeks a mate, after which the female selects the underside of a leaf, often in a sunny patch of nettles, to lay a cluster of eggs. Caterpillars hatch after two or three weeks and build a web at the top of the nettle plant to provide them with protection from predators while they feast on the leaves. Once they are fully grown they leave the communal group before selecting a suitable site for pupation, a stage which lasts for up to four weeks depending on the temperature. The new butterflies emerge during July and August and spend the rest of summer gorging themselves on nectar to prepare for hibernation.
Often seen feeding from the same plants as peacock and small tortoiseshell butterflies is the migratory red admiral, which has vivid slashes of reddish orange across its black wings. All of these butterflies are likely to be seen in any garden or park, alongside several other species including orange tips, meadow browns and the ghostly small and large whites, whose caterpillars' eating habits have earned them the nickname ‘cabbage whites'. Many less common British butterfly species can only be seen in quite specific locations. Our largest native butterfly, the swallowtail (pictured left), is found solely on the Norfolk Broads where it seeks out the nectar of pink or mauve flowers such as ragged robin and thistle. With a wingspan of eight or nine centimetres you'd be forgiven for thinking it was a tropical species with its cream and black patterned wings with distinctive tail and bright blue and red ‘eye' markings.
Read the rest of this feature on p.102 of the July/August 2014 issue...
By Nicola Beaverstock
Images courtesy of The Wildlife Trusts: Amy Lewis, Janet Packham, Margaret Holland, Richard Bowler