Britain's Butterflies is a comprehensive and beautifully designed photographic field guide to the butterflies of Britain and Ireland. Containing hundreds of stunning colour photographs, this revised and updated edition provides the latest information on every species ever recorded. It covers in detail the identification of all 59 butterfly species that breed regularly, as well as four former breeders, 10 rare migrants and one species of unknown status. The easy-to-use format will enable butterfly-watchers—beginners or experts—to identify any species they encounter.
- Stunning colour plates show typical views of each butterfly species, including the various forms and aberrations
- Detailed species profiles cover adult identification; behaviour; habitat requirements; population and conservation; egg, caterpillar and chrysalis; and status and distribution, including up-to-date maps
- Photographs of egg, caterpillar and chrysalis for every breeding species
- Sections on biology, where to look for and how to identify butterflies and other essential information
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A Field Guide to the Butterflies of Britain and Ireland
By David Newland, Robert Still, Andy Swash, David Tomlinson
PRINCETON UNIVERSITY PRESSCopyright © 2015 David Newland, Robert Still, Andy Swash and David Tomlinson
All rights reserved.
How butterflies and moths differ
Butterflies and moths are members of a huge number of some 165,000 insects known as the Lepidoptera. The word lepidoptera is constructed from Greek words meaning 'scale' and 'wing' and is now used to describe all insects which have four scale-covered wings. From it is derived the word lepidopterist for someone who specializes in studying these insects.
Butterflies reach their greatest diversity in the tropics. The islands of Trinidad and Tobago, for example, boast more than 600 species of butterflies, yet Britain and Ireland has only about 60 species, despite the land mass being 20 times greater. In Europe, there are some 440 species.
How butterflies and moths differ
Distinguishing butterflies and moths is not always easy, for the two are closely related. The easiest way to recognize a butterfly is to look at its antennae: those of butterflies having clubbed ends, whilst those of moths are fine and often feathery. In addition, a butterfly sleeps with its wings held tightly together vertically above the body. In contrast, a moth usually roosts with its wings held horizontally flat over the body, the forewing largely obscuring the hindwing.
Butterflies rarely fly at night, and many will only fly in bright sunshine. Moths fly mainly at night, but the few day-flying species can be readily recognized as moths by their antennae and resting posture. Of course, as in most classifications in nature, there are exceptions. Dingy Skipper butterflies often rest in a moth-like pose, but they have clubbed antennae. Day-flying burnet moths have antennae that can be described as clubbed, but they always rest with their wings in the typical moth posture.
This section of the book provides an introduction to the biology and ecology of butterflies. The diagram opposite illustrates the life-cycle of a butterfly, and the following sections detail the egg, larval, emergence and adult stages.
Butterfly eggs come in many shapes and sizes depending on the species (see pages 207–211).
Eggs are very small, usually less than 1 mm across their longest dimension. Although shapes, colours and sizes may differ, the structures are similar, comprising a hard outer case inside which is contained, much like a chicken's egg in miniature, an embryo surrounded by a nutritious fluid. Once fully formed, the caterpillar chews its way out of the egg, the remains of which it often eats.
Eggs are laid singly, in small groups or large clusters, depending on the species involved. The eggs are almost always laid on, or very close to, the plant upon which the caterpillar will feed. The eggs usually hatch just over a week after being laid, except for those that overwinter. Usually, a high proportion of the eggs hatch, although some are lost to adverse weather, become victims of parasites or are eaten by predators. Female butterflies take great care in selecting locations where their eggs are most likely to survive.
Each egg hatches into a caterpillar.
Once the caterpillar has emerged, it uses its strong jaws to feed on plant matter. Caterpillars come in many shapes, sizes and forms (see pages 212–218). They are vulnerable and their look and behaviour is designed to maximize their chances of survival.
Many are spiny or hairy to deter predators, some are poisonous, and some (such as the High Brown Fritillary (page 118) that resembles a Bracken frond) are camouflaged to help them avoid being detected. In some species, caterpillars live together under the relative safety of a silken web, while other species live within blades of grass that they have rolled to create a tube.
When small, caterpillars can fall victim to spiders and other insects, and, when larger, to birds and small mammals.
Each species has a preferential plant or range of plants that it feeds on (see pages 194–205) and many require very specific habitats and weather conditions. As they grow, caterpillars shed their flexible skin between three and six times, depending on the species.
When fully-grown, after a few weeks or several months (again depending on the species), the caterpillar anchors itself firmly and sheds its skin for the last time to reveal the soft casing beneath and enters its third (and inactive) stage, the chrysalis.
The young chrysalis is soft, but in time, the skin hardens. A typical chrysalis (see pages 219–224) is well camouflaged to avoid predators because it can no longer move and has no active defence mechanism.
During the next few days or weeks, its cells are miraculously rearranged and it changes from a caterpillar into a butterfly, with its newly-formed wings crushed tightly within the chrysalis's casing.
This transitional stage, otherwise known as pupation, is also fraught with danger. A large proportion of chrysalises fall prey to birds and small mammals.
Whilst some species form their chrysalises on fence-posts and walls and are surprisingly conspicuous, the chrysalises of others are well camouflaged. For example, the Black Hairstreak mimics a bird dropping and the White Admiral resembles a rolled-up Honeysuckle leaf.
Others are formed in dense vegetation or leaf-litter and some, like the skippers, spin silken cocoons around blades of grass, within which they pupate.
When mature, the chrysalis casing bursts and the adult butterfly emerges. Its wings expand as fluid is pumped into their veins.
After emergence, the adult takes up to an hour to expand its wings and be strong enough for flight. Once on the wing, the adult butterfly moves off to feed, find a mate and reproduce, starting the life-cycle all over again.
Many butterflies have a remarkably short adult life. For a number of species, such as blues and hairstreaks, it can be as brief as four or five days. Others, such as the larger fritillaries and the Swallowtail, might live for two or even three weeks, but few survive as long as a Brimstone, which can live for up to ten months (although most of this time is spent in hibernation).
Butterflies do not grow once they have emerged, and need to feed purely to maintain their strength to fly, find a mate and lay eggs.
Males often emerge before females. This head start gives them time to set up territories, and ensures that every emerging female is mated quickly. Once the female butterflies have laid their eggs, their biological function has been fulfilled. Male butterflies have a priority to mate with as many females as possible, and their patrolling flights are a constant search for virgin females. Males have special scales on the upperside of the forewings that produce scents (pheromones) which attract females. In most species, the wing patterns of males and females are significantly different to allow them to recognize one another.
The main threat to adult butterflies is predation. A wide range of bird species, including many summer visitors, time their breeding to coincide with peak insect emergence. Often you will see butterflies with parts of their wings missing, testimony to a narrow escape from, for example, a Spotted Flycatcher or a Great Tit.
Caterpillar foodplants (see pages 194–205)
Female butterflies invariably lay their eggs on, or close to, their caterpillars' foodplant, which might be a flower, grass, shrub or tree. Most butterflies depend on just one or two favoured foodplants, though some are less fussy. Large Whites, for example, lay their eggs on a wide range of brassicas, including Cabbages, Kale and Brussels-sprouts, but they will also use garden Nasturtiums. Such flexibility has ensured the widespread success of this species, as well as its unpopularity with gardeners! In contrast, British Swallowtails lay their eggs almost exclusively on Milk-parsley, a very localized fenland plant, thus restricting where they can breed. Curiously, continental Swallowtails use a wide range of plants, chiefly of the Umbelliferae family, which explains why this butterfly is much more widespread in Europe than it is in Britain. Similarly, six species of fritillary exclusively use violets and a further 12 British butterflies are reliant upon only one species of caterpillar foodplant. Some of those butterflies that rely on a single or limited range of foodplants that grow only in specific conditions are put at serious risk of local extinction by any changes in habitat that affect their foodplant. However, others that use mainly one foodplant are unlikely to suffer in this way if their foodplants are common and widespread.
Adult food sources (see pages 202–205)
Most adult butterflies need nectar for survival, although some, including the Black Hairstreak and Purple Emperor, drink mainly the sugary honeydew secretions left on leaves by aphids. The range of nectar plants used by some common butterflies is huge, whilst other butterflies use just a few species. The Small White uses a wide range, but is particularly attracted to both white and pink flowers. In contrast, Glanville Fritillary prefers only a few, usually Thrift and Common Bird's-foot-trefoil.
Camouflage and defence
As well as the perils of adverse weather, butterflies fall victim to predators and parasites throughout their life-cycle.
In response, the caterpillars, chrysalises and adults of some species have developed remarkable camouflage to help them avoid detection. As examples, caterpillars of the Purple Emperor resemble, in colour and markings, the leaves of their foodplant. Brimstone caterpillars lie along the midrib of a leaf, which they closely resemble, and are not easy to find. As well as camouflage, some caterpillars have other defence mechanisms. Some are avoided by predators as they are poisonous, some are distasteful, and others are hairy or spiny and difficult to swallow. The strategy adopted by the very conspicuous Swallowtail caterpillar, if threatened, is to erect a 'horn' on its head, called its osmeterium, which emits an unpleasant smell.
In some species, such as the Green-veined White, the chrysalis matches the colour of its surroundings, ranging from green to pale brown. Other species have chrysalises that look like dead leaves, buds, seedpods and even bird droppings. All are a challenge to locate for even the most determined butterfly enthusiast.
Adult butterflies tend to be far more conspicuous than all the other life-cycle stages. They have to balance the demands of defending territories, looking for mates and egglaying with the threat of predation. Almost always, females are less conspicuous than males. For example, female blues are in fact brown rather than blue. Also, the females of some species, for example certain of the skippers and fritillaries, often stay out of sight amongst ground vegetation for long periods. Many species have 'eye' spots on their wings that deceive predators into thinking that a butterfly is bigger than it actually is. The Peacock has the largest such 'eyes' of our butterflies and, if a predator approaches, the butterfly will open and close its wings rapidly to reveal these 'eyes', whilst making a scraping sound by rubbing its forewings and hindwings together.
Living with ants
The life-cycle of a number of butterflies (particularly the blues) is linked inextricably with certain species of ants. For example, Chalkhill Blue caterpillars emit sweet liquids from a gland that attracts the ants day and night. The ants' attendance helps the caterpillar's chances of survival, probably because the ants keep predators and parasites away.
The Large Blue is a species that has been studied extensively in connection with its managed return from extinction in Britain. It is unable to survive without a particular species of red ant (Myrmica sabuleti). These carry Large Blue caterpillars into their nests. When the caterpillar is just a few millimetres long it drops from its foodplant to the ground and waits to be discovered by an ant. When discovered, the caterpillar releases a droplet of sweet liquid that the ant drinks before recruiting other worker ants into a feeding frenzy. After a period of up to four hours, the caterpillar then adopts a posture which mimics an ant grub. That encourages the ant to pick up the tiny caterpillar in its jaws and carry it into the ants' nest where it is deposited amongst the ant grubs' Such a practice does not benefit the ants in the long-term, as the caterpillar spends the next few months feeding on ant grubs in the nest.
Living through the winter
In some species, adult butterflies hibernate, but the majority overwinter as a caterpillar, chrysalis or egg. Surviving the winter, in whatever stage, is a stern test. The entire population of most species exists in one stage only at this time. An exception is the Speckled Wood which overwinters either as a chrysalis or as a caterpillar, the chrysalis dormant and the caterpillar resting at the base of a plant, feeding if the temperature rises above about 6 °C.
Eggs that overwinter have thicker shells than those that do not. In some species, the overwintering egg actually contains a fully-formed caterpillar, hibernating in safety before emerging in the spring.
The caterpillars of some butterflies spin a chamber of silken threads around vegetation, such as blades of grass or the leaves of the foodplant, in which they pass the winter.
For species that overwinter as a chrysalis, these are often situated close to the ground, in leaf-litter or in thick vegetation, where the climatic conditions may be less extreme. Large and Small Whites are two species that overwinter as chrysalises and these can sometimes be found on walls and under window ledges. Butterflies that go through the winter as adults, like Brimstones, Peacocks and Small Tortoiseshells, feed avidly prior to hibernation, so that they build up enough fat reserves to last them through the winter.
Brimstones hibernate from August through to the first warm days of spring in February or March. They hide in thick patches of Holly, Ivy and sometimes Bramble. Peacocks like sheds and dark crevices, while Small Tortoiseshells will often enter inhabited dwellings to find their home for the winter. During the winter, adverse weather such as a prolonged freeze, damp spell or flooding can destroy a large proportion of a hibernating colony.
Though the majority of Britain and Ireland's butterflies are resident, and many rarely move more than a few hundred metres from where they first emerged, a number are highly migratory. It is rare, for example, for Red Admirals to hibernate successfully in Britain, so the butterflies we see each summer are the offspring of migrants that have crossed the English Channel from continental Europe earlier in the season. Similarly, our populations of Clouded Yellows and Painted Ladies are dependent upon migrants from the continent, as neither species is thought to overwinter successfully in Britain. Though the migration is principally northerly, there is also a noticeable southward movement undertaken by such butterflies as Red Admirals and Painted Ladies in the autumn. How many manage to return to mainland Europe is unknown.
Some butterflies only reach Britain or Ireland as rare migrants (see pages 160–191). The best-known example is the Monarch (page 188), a migrant from North America that is now resident in Madeira, the Canary Islands and along the Mediterranean coast. But several other species, such as the Long-tailed Blue (page 170) and Camberwell Beauty (page 186), may wander to Britain, often wind-assisted, from just across the English Channel.
There are also some extreme rarities (see page 160) that have been recorded, usually as a result of unusual weather conditions combined with a good year for the species.
Where to look for butterflies
Some of our butterflies wander from place to place. These are the species that are encountered most readily, such as Brimstone, the whites, Orange-tip, Holly Blue, Red Admiral, Small Tortoiseshell, Peacock, Comma and Meadow Brown. You may find these anywhere. An average-sized garden, with the right plants (see opposite) will attract a dozen or more different species during the year. Always keep a look out, as species will occasionally turn up in the most unlikely places. Where there has been extensive arable farming, there will not be many butterflies unless wide hedgerows remain, but elsewhere butterflies have evolved to occupy almost every wild and semi-natural habitat in Britain and Ireland. The key to finding many species is knowing which habitat or habitats they prefer because, unlike those listed above, most of the other species are colonial and are very fussy about where they live.
Excerpted from Britain's Butterflies by David Newland, Robert Still, Andy Swash, David Tomlinson. Copyright © 2015 David Newland, Robert Still, Andy Swash and David Tomlinson. Excerpted by permission of PRINCETON UNIVERSITY PRESS.
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Table of ContentsForeword 7
How butterflies and moths differ 12
The life-cycle of a butterfly 14
Butterfly biology. 15
Where to look for butterflies 24
Gardening for butterflies 25
Butterfly habitats 26
Favoured habitats 32
Key places for rare and localized butterflies 33
How to identify butterflies 34
Key features of adult butterflies 34
Butterfly identification 35
Colour variation: forms and aberrations 36
The types of butterfly 38
THE SPECIES ACCOUNTS 41
Species of doubtful provenance 192
Caterpillar foodplants 194
Butterfly nectar sources and caterpillar foodplants 202
Eggs, caterpillars and chrysalises. 206
List of British and Irish butterflies. 225
Butterfly watching and photography 230
Butterfly Conservation 231
Recording and monitoring 231
Conservation and legislation 232
Further reading 234
Sources of further information and useful addresses 235
Acknowledgements and photographic/artwork credits 236
Index of English and scientific names 239
What People are Saying About This
"This beautifully produced book, rather than being just an identification guide, is more a reference work for both the enthusiastic amateur and the expert."Anthony Toole