The Hesperioidea comprises of a single family, the Hesperiidae. The Papilionoidea were traditionally divided into 5 individual families – Papilionidae, Pieridae, Lycaenidae, Riodinidae and Nymphalidae. In 2011 however phylogeneticists discovered as a result of molecular analysis that the moth family Hedylidae had more in common with the 5 ‘butterfly’ families than with other moths. Consequently they were transferred to the Papilionoidea, and are now commonly known as butterfly-moths!

Hesperiidae – The classification proposed by Evans has been shown by later revisionists to be unreliable. In this treatment I follow the arrangements of Mielke, Austin, Lamas and Warren. There are about 4130 known species of Hesperiidae worldwide. Members of this family have a characteristic rapid darting flight, hence they are popularly known as skippers or darts. Many of the South American species are brightly coloured, but elsewhere most species are brownish and quite drab in appearance. Compared to other butterflies, skippers have stout bodies and large eyes. They also have widely separated antennae that are usually tipped with a hooked club. The larvae of most species live in shelters or tubes constructed from the foliage of their foodplants. The pupae are usually formed loosely within a frail silk cocoon.

	Pyrrhopyginae – Swifts, Sabre-wings Jemadia menechmus ( Peru ) A subfamily confined to South America and the part of Central America south of the Rio Grande, Mexico. There are 168 known species. Genera include Myscelus, Passova, Zonia, Pyrrhopyge, Jemadia & Mysarbia. The butterflies are very stout-bodied, and average 40-60mm in wingspan. They fly powerfully around the forest canopy, but descend to feed at mud or bird-droppings.
	Pyrginae – Flats, Spreadwings Pyrgus malvae ( England ) Pyrginae are represented in all temperate and tropical areas of the world. They commonly bask on the ground or on foliage with their wings held flat. Many tropical species habitually rest under leaves with wings outspread. Species from temperate regions often roost overnight on dead flower-heads. The males of many genera have a small fold on the leading edge of the forewings, containing androconial scales.
	Heteropterinae – Chequered Skippers Dalla cypselus ( Peru ) The Heteropterinae are a fairly small sub-family comprised of about 140 neotropical species, and 30 or so in the Holarctic region. They are all small butterflies, averaging between 30-40mm in wingspan. Most have dark brown uppersides, dappled with cream or orange spots. The larvae of all species feed on grasses.
	Hesperiinae – Grass Skippers, Trapdoor Skippers Ochlodes sylvanus ( England ) All Hesperiine larvae feed on monocotyledons. Adults of most species have fuscous or chocolate wings, often marked with pale spots or hyaline windows. When resting they hold their wings erect, or adopt the posture illustrated here. Temperate species commonly nectar at flowers, but those from tropical areas feed at mud, rotting vegetation or bird droppings. The former subfamily Megathyminae is now included in the Hesperiinae.
	Trapezitinae – Australian Skippers Trapezites symmomus ( Australia ) A group of about 60-70 smallish, heavy-bodied skippers, all of which are confined to the Australian/Papuan region. Unlike the Hesperiinae, males of Trapezitinae do not possess androconial sex brands. There are 18 genera. Trapezites is the largest, with between 15-18 species depending on taxonomic interpretation. Each genus of the Trapezitinae specializes on particular larval foodplants, e.g. Trapezites all feed on spike rush Lomandra.
	Coeliadinae – Policemen, Awls The Policemen and Awls are a group of large robust skippers with a fast whirring flight similar to that of hawkmoths. They are active from dawn to early evening, and frequently visit flowers for nectar. There about 75 species worldwide – 18 in Africa, 12 in Australasia, and about 45 in the Oriental region.
	Euschemoniinae – Regent Skipper Euschemon rafflesia ( Australia ) This subfamily contains just one species -the Regent Skipper Euschemon rafflesia, an Australian insect in which the fore and hindwings are coupled together in flight by a frenulum- a feature found in all moths, and in the ‘butterfly-moths’ Hedylidae, but not in the 5 traditional butterfly families.
Papilionidae – Here I follow the classification adopted by Tyler, Doubleday and Lamas. There are about 590 known species of Papilionidae worldwide. The majority are large colourful butterflies. Many have short tail-like extensions on their hindwings, and hence are popularly known as swallowtails. The caterpillars can be either cryptically coloured or aposematic, depending on subfamily and tribe. All Papilionid caterpillars possess an extrusible organ called an osmaterium, which exudes foul smelling scents to deter predators and parasitoids. The pupae of all species are cryptically coloured, and are usually formed head-upwards, attached by the cremaster and a silk girdle to a leaf or stem.
	Papilioninae – Swallowtails, Birdwings, Dragontails Papilio machaon gorganus ( France ) About 540 medium or large species, found throughout the tropical, temperate and sub-arctic regions of the world. The exquisite Dragontails of the Oriental region zip back and forth very rapidly, and resemble dragonflies in flight. Most others including the Swallowtails and the spectacular Birdwings of New Guinea, have a fast fluttering flight, and keep their wings constantly in motion when nectaring.
	Parnassiinae – Apollos Parnassius apollo ( France ) About 50 species found in alpine and sub-arctic regions of the northern hemisphere – 3 in North America, 3 in Europe, and the remainder in mountainous regions of temperate Asia. All species are poisonous to vertebrates. Most have semi-transparent whitish wings, marked with prominent red or orange ocelli.
	Baroniinae Baronia brevicornis ( Mexico ) A sub-family erected to accommodate a single species, Baronia brevicornis, a locally common endemic of the mountains of western Mexico. It is a smallish butterfly, marked with pale yellow patches on a brown ground colour, and is characterised by having extremely short antennae.
Pieridae Here I retain the classification proposed by Klots. The Pieridae comprises 1036 described species worldwide and includes the whites, yellows, orange tips, ithomiine-mimics and jezebels. Their eggs are spindle-shaped and vertically ribbed. The larvae of most genera are cryptically coloured, naked or slightly hairy, and without appendages. The pupae are also cryptically coloured, and attached head-upwards by the cremaster and a silken girdle to the substrate.
	Coliadinae – Sulphurs, Yellows, Brimstones Gonepteryx rhamni ( England ) The Coliadinae are found on all continents. Most species are strongly migratory, including the Grass Yellows and Sulphurs, which migrate seasonally along the routes of rivers, and settle in vast numbers on the sandbanks of Amazonian tributaries. Other species such as the Brimstones, are nomadic by nature, and very adaptable to different environments.
	Pierinae – Whites, Orange-tips, Jezebels, Pereutes Anthocharis cardamines ( England ) The Pierinae are very cosmopolitan of all butterflies, having representatives occurring on all continents and in all habitats including tropical rainforests, temperate woodlands, alpine pastures, deserts, moorland and tundra. Most have a white ground, often marked with black, yellow or orange. They include the Orange tips, Whites, Arabs, Vagrants, Dotted Borders, Flip-Flops and Jezebels.
	Dismorphiinae – Wood Whites, Mimics Leptidea sinapis ( England ) The name Dismorphiinae refers to the fact that many members of this predominantly tropical group are sexually dimorphic – i.e. the males and females differ markedly in appearance. Many are also mimetic, e.g. Patia orise from Brazil is an almost perfect mimic of the Ithomiine Glasswing Methona confusa.
Lycaenidae There are about 4500 described species of Lycaenidae worldwide, although the number of known species is increasing rapidly as a result of work by Robbins and others in the neotropics. The adult butterflies are generally small and brightly coloured, often with metallic blue or coppery uppersides. The larvae are typically slug-shaped, cryptically coloured, and often resemble leaf blisters or buds. In most cases they live in association with ants, which milk their honey glands to obtain a sugary secretion. The ants coincidentally act as guards, protecting them from predatory insects. In many species the relationship is complex, and can involve the larvae living within ant nests, and feeding carnivorously on ant grubs. Other species feed on aphids or fungi cultivated by ants. The pupae do not possess a cremaster. In some species they are formed loosely on the surface of the ground. In others they are attached by a silk girdle to a leaf or stem. This treatment follows Robbins’ revision of the Theclinae. The remaining sub-families follow the classification used by Lamas et al.
	Theclinae – Hairstreaks, Sunstreaks, Oakblues etc. Thecla betulae ( England ) The Theclinae comprises about 2000 species worldwide, over 1100 of which occur in the neotropics. They are commonly known as hairstreaks, a name derived from the white hair-line streaks found on the undersides of most species. Another common characteristic is the presence on most species of tails on each hindwing. The butterflies are noted for their fast and very erratic flight around bushes and trees.
	Polyommatinae – Blues, Arguses, Caeruleans Polyommatus icarus ( England ) Polyommatinae means “many-spotted”, and refers to the pattern of small dark spots or blotches on the undersides of most species. Males generally have blue uppersides, while females tend to be brownish, often with orange or red sub-marginal lunules. The butterflies primarily breed in grassland or sub-alpine habitats, and visit flowers for nectar.
	Lycaeninae – Coppers, Sapphires, Silverlines Lycaena phlaeas ( England ) The Lycaeninae are found mainly in grassland, moorland and marshland areas of the Holarctic region, although a few species occur in the tropics and in New Zealand. Most species have fiery copper uppersides, often with dark borders and a pattern of dark spots. Males typically set up territories, voraciously defending them against any intruding insect.
	Poritiinae – Gems Poritia phormedon ( Borneo ) The Poritiinae are exclusively Asian, with about 30 species found from Assam to Malaysia, the Philippines and Sulawesi. All are very rare, and found in rainforests and cloud-forests up to an elevation of about 2000m. All Poritiinae species are sexually dimorphic. Males are marked with iridescent blue or green, while females are marked with small patches of white, orange or red, depending on species.
	Miletinae – Brownies, Darkies Allotinus horsfieldi ( West Malaysia ) A fascinating group of small delicate butterflies, mottled or stippled with brown on a whitish ground colour. There are about 80 species in south-east Asia, 45 in Africa, and one in North America. The larvae of all species are carnivorous, feeding on aphids and other Homoptera, although one Sumatran species lives in ant nests and feeds on the grubs.
	Curetinae – Sunbeams Curetis santana ( Singapore ) This sub-family comprises of a single genus, Curetis, with 15 known species, found in rainforest, tropical dry forest and coastal habitats in the Oriental region. Males have fiery iridescent copper uppersides, but the females are brown, with large yellowish or white patches, and can be mistaken for small Pierids when in flight.
	Lipteninae – African Liptenids Epitola posthumus ( Ghana ) An exclusively African subfamily of 522 species, found mainly in the rainforests of Ghana, Cameroon, Gabon and the Congo. The larvae feed on lichens. The butterflies are small and often brilliantly coloured. They are sometimes seen flying around the trunks of fig trees, or settled on dry twigs. If disturbed by ants, they remain on the twigs, slowly fanning their wings.
	Liphyrinae – Moth butterflies Liphyra brassolis ( Sumatra ) A small sub-family comprising of 22 small stout-bodied African species, and 3 Liphyra species including the “moth butterfly” Liphyra brassolis. Its larvae live during the latter part of their lives in nests of the weaver ant Oecophylla smaragdina. They are smooth, elliptical and flattened, with a hard shell which protects them from being attacked by the ants. The adult butterflies lack a proboscis and cannot feed.
Riodinidae This family was in the past known as the Eryciinidae or Nemeobiidae and is regarded by some as being a sub-family of the Lycaenidae. In this treatment I follow Stichel, Harvey, Hall, d’Abrera, Lamas, Willmott and Callaghan, who regard it as a family in it’s own right. There are about 1500 species of Riodinidae, the vast majority of which are confined to the neotropical region. They are generally small in size, but very diverse in shape, colour and pattern. Many have metallic green, blue or orange areas on the uppersides, hence they are popularly known as metalmarks. Some species have long tails on the hindwings and resemble miniature swallowtails. Metalmark larvae are similar to those of the Lycaenidae, but do not normally associate with ants. In many neotropical species the larvae are adorned with prominent tubercules or other protuberances. As with the Lycaenidae, the pupae do not possess a cremaster, and according to species are either formed loosely on the surface of the ground, or are attached by a silk girdle to a leaf or stem.
	Riodininae – Metalmarks, Underleafs, Doctors etc. Hamearis lucina ( England ) The Duke of Burgundy illustrated here is the only European member of the Riodinidae. In South and Central America there are 1150 known species in the sub-family Riodininae. Most are roughly similar in size to the Duke of Burgundy, but many are marked with metallic green, blue, purple, copper and red scales, and are commonly known as metalmarks.
	Euselasiinae – Euselasias Euselasia gelanor ( Peru ) This sub-family is confined entirely to the neotropical region. There are 172 known species. The butterflies range between about 25 – 40mm in wingspan. They habitually hide under leaves, with their wings held erect, occasionally darting out to investigate other butterflies. The undersides are generally marked with vertical bands in shades of brown, white and orange, but the uppersides are typically black or chocolate, with large patches of bright red or iridescent blue.
Nymphalidae Many of the sub-families described below were previously considered to be families in their own right. In this treatment I follow Wahlberg’s 2008 classification in which the 6000 Nymphalid species are divided into 12 subfamilies. These each have their own distinctive characteristics but are united by one common feature – the forelegs of the adults are greatly reduced in size and are useless for walking. In males they are reduced to such a degree that they are little more than hairy stumps, hence the popular term ‘brush-footed’ butterflies.
	Libytheinae – Beaks Libythea myrrha ( West Malaysia ) A very small sub-family with only 19 species worldwide, but represented on all continents and on many islands. Some taxonomists still consider Libytheidae to be a full family. The butterflies are characterised by having very long beak-like labial palpi. When at rest the jagged brown wings take on the appearance of dead leaves, with the “beak” resembling a leaf stalk.
	Nymphalinae – Aristocrats, Checkerspots etc Inachis io ( England ) The Nymphalinae includes many of the world’s most familiar species, including the Peacock, Red Admiral & Painted Lady. Other representatives include the genera Junonia, Siproeta, Anartia, Kallima, Hypolimnas and the smaller Fritillaries in the genera Euphydryas, Chlosyne, Melitaea and Mellicta, all of which were formerly included in the now defunct sub-family Melitaeinae.
	Heliconiinae – Longwings, Fritillaries etc Argynnis paphia ( England ) A contentious combination of taxa including about 70 species of Heliconiini – neotropical rainforest species marked with patches of cream, red and blue; and the Argynnini which comprises of about 70 black-spotted temperate woodland butterflies, typified by the Silver-washed Fritillary illustrated here.
	Acraeinae – Acraeas, Altinotes etc Acraea bonasia ( Ghana ) Some workers regard the African Acraea and South American Altinote / Actinote / Abananote genera as being members of the tribe Acraeini, which they place in the subfamily Heliconiinae. Recent DNA research however indicates that they are distinct from the Heliconiinae, thus I treat them here as members of the subfamily Acraeinae.
	Limenitidinae – Gliders, Sailors, Sisters, Foresters Adelpha capucinus ( Peru ) In 2003 Wahlberg reclassified the Limenitidinae, excluding many genera which are now reassigned to the Biblidinae. The revised arrangement is more rational, including only a few very obviously related genera e.g. Adelpha, Limenitis, Neptis, Athyma and Moduza. All are forest dwelling species noted for their graceful flight and distinctive uppersides, banded with white and / or orange.
	Biblidinae – Crackers, Numberwings Diaethria clymena ( Peru ) The Biblidinae are a large group of very colourful forest butterflies which to the layman have few obvious features in common. The vast majority of genera such as Diaethria, Nessaea, Hamadryas & Panacea are restricted to the neotropics although a few genera including Ariadne & Neptidopsis are found in Africa.
	Cyrestinae – Daggerwings, Mapwings, Maplets Marpesia petreus ( Peru ) The subfamily Cyrestinae include the spectacular Marpesia Daggerwings of the neotropics, which roost overnight in clusters of up to 50, hanging beneath leaves. Also included are the oriental Cyrestis Mapwings & Chersonesia Maplets, which commonly rest under leaves, with their wings fully outspread.
	Apaturinae – Emperors, Princes, Doxocopas Apatura iris ( England ) There are about 50 species of Apaturinae worldwide, all forest dwelling butterflies noted for their with powerful flight. Males obtain their sustenance from minerals dissolved in mud, sap, rotting fruit, carrion or dung, and transfer the proteins to females during copulation. Neither sex visit flowers. Males of Apatura and Doxocopa display a brilliant purple, blue or green sheen when viewed at certain angles.
	Charaxinae – Leafwings, Pashas, Preponas, Agrias Archaeoprepona amphimachus ( Peru ) Only one member of the Charaxinae is found in Europe, Charaxes jasius. The majority of species are restricted to tropical / sub-tropical areas, with the greatest concentrations in Africa and South America. They are powerful flyers, found primarily in rainforest and tropical dry forest habitats. Many have convincing “dead-leaf” undersides, but some such as Agrias have intricate patterns in red, cream and blue. The uppersides usually have bright blue or red bands or patches.
	Satyrinae – Browns, Phantoms, Palmflies Melanargia galathea ( England ) Satyrine larvae feed on grasses, palms or bamboos. In the Holarctic region the subfamily is represented by the Browns, Heaths, Ringlets, Marbled Whites & Graylings. Their African and tropical Asian counterparts include ringlet-like genera such as Ypthima & Mycalesis. South America has by far the greatest diversity, with the transparent Cithaerias, skulking Pierella, and Euptychia ringlets being well known examples.
	Morphinae – Morphos, Owls, Jungle Glories Caligo oileus ( Peru ) The Morphinae includes some of the largest & most dazzling butterflies on Earth – the enormous iridescent blue Morpho butterflies which flap slowly along river courses in Central & South America. Other members of the subfamily include the Jungle Glories of Asia ( Amathusiini ), and the neotropical Caligo Owl butterflies ( Brassolini ). The huge “owl” eyespots of the the latter serve a dual role – acting as a threat when intimidated, and as decoys in the event of attack. Recent molecular study strongly suggests that the Morphinae are a tribe of Satyrinae.
	Danainae ( Danaini ) – Monarchs, Tigers, Crows Danaus genutia ( West Malaysia ) There are about 200 species of Danaini. Only 2 species have been recorded in Europe – Danaus plexippus and D. chrysippus. The larvae of all species assimilate toxins from their foodplants, and pass them on to the adult butterflies, rendering them unpalatable to birds. This unpalatability is advertised by the bright orange and black patterning on the wings, which in turn is mimicked by various other toxic and non-toxic species from other sub-families.
	Danainae ( Ithomiini ) – Glasswings, Tiger-mimics Ithomia terra ( Peru ) Ithomiines fall ( unscientifically ) into 2 groups – the orange and black banded Tiger-mimics, and the transparent Glasswings. They occur exclusively in neotropical rainforests and cloudforests. The adult males feed at Heliotropium and Eupatorium to obtain pyrrolizidine alkaloids, which they chemically convert into pheromones. They gather at “leks” to release their pheromones to attract mates.
	Danainae ( Tellervini ) – Hamadryads Tellervo assarica ( New Guinea ) The Tellervini was originally thought to comprise of a single Australasian species Tellervo zoilus, with 9 subspecies. Recent research however has led to all of these being elevated to full species status. The butterflies are allied to the Danaini and Ithomiini, but differ morphologically from both in several respects. They are found in Queensland, Papua and the Solomon Islands.
Hedylidae The 35 species of the family Hedylidae are nocturnal and moth-like in appearance. The early stages however have many butterfly-like characteristics. The eggs for example are structurally closer to those of Pieridae and Nymphalidae than to moth eggs. The caterpillars have horn-like processes like Apaturinae, a bifid tail as found in Satyrinae, and secondary setae as found in Pieridae. They also have an “anal comb” used for expelling droppings – a characteristic of the Hesperiinae. The pupae likewise have structural characteristics more representative of butterfly pupae, and are secured to the substrate with a silken girdle, just like those of the Pieridae and Papilionidae.
	Hedylidae – Butterfly-moths Macrosoma heliconaria ( Peru ) The Hedylidae have not yet been assigned any subfamilies or tribes. All Hedylidae are placed in the same genus – Macrosoma. There are 35 species distributed variously from Mexico to Bolivia. The greatest concentration is in southern Peru where at least 26 species occur.

In past times any two butterflies that looked identical in structure and markings were assumed to be the same species, and named accordingly. However we now know that there are many species involved in “mimicry rings” whereby several different species can produce visually identical adults.

Conversely we also know that it is quite common for a single species to produce several different forms or morphs, which previously might have been classified as different species. A good example of this phenomenon is the African Mocker Swallowtail Papilio dardanus – the male is cream in colour and possesses tails on the hindwings.

The female however lacks tails, and produces several forms, each differing in colour and pattern, but all mimicking various species from the Danaine genera Danaus and Amauris, and the Acraeine genus Bematistes.

Another problem with morphological species is that apparently identical adult butterflies can have early stages ( eggs, caterpillars, chrysalises ) that differ in structure. Taxonomists therefore began to examine the full lifecycle rather than just the adult butterflies, and consequently several new species were discovered, e.g. the Clouded Yellows Colias alfacariensis and C. hyale were thought to be the same species until Berger discovered distinct differences in the larvae and pupae.

Closely related morphological species can sometimes be visually indistinguishable, making it almost impossible to determine whether they represent varieties / subspecies of one butterfly, or whether they are biologically different ( but visually identical ) species.

Biological species

These are defined as creatures which breed with other biologically identical creatures, and produce fertile offspring. To prevent interbreeding, each species of butterfly has uniquely shaped genitalia – the male “key” only fitting the correct female “lock”. The males and females of some butterflies are totally different in appearance, and may not initially be recognized as belonging to the same taxon. By examining the genitalia, taxonomists have often discovered that 2 insects previously classified under entirely different genera are actually the same biological species!

Hybrids

Despite Nature’s mechanisms for the prevention of interbreeding, hybridization between species does occasionally occur. Hybrids however are always infertile, so they are unable to pass on their characteristics to another generation.

Cladistics and phylogenetics

Cladistics is a system whereby comparative data is analysed quantitatively and is used to construct cladograms, dendrograms and matrices. These are visual representations of the evolutionary tree of life and are used to depict the assumed evolutionary relationships between groups of organisms.

In simple terms, if two sample specimens were analysed and found to share only a low number of common characteristics, this would imply that they were only distantly related, i.e. that they split from their common ancestor a very long time ago. At the other extreme, if the number of shared characteristics was high it would imply that the specimens were closely related, having split from a common ancestor relatively recently.

Hence they would probably be placed in the same genus. For both insects to be recognised as the same species, ALL of the characteristics would of course have to be identical.

Since the late 20th century phylogenetic analysis has increasingly been used to differentiate species and to establish evolutionary relationships between various subfamilies and genera. A biologist will typically begin by analyzing 100 or so different characteristics. These could include anything from the spikes on a butterfly’s leg to the structure of the eyes, the presence or absence of a branching wing vein, or the chemical content of the larval foodplants.

From this initial list of 100 characteristics the biologist will then select about 40-50 that experience indicates should be the most reliable for the final analysis.

These are each weighted according to their perceived relevance to the study. Computers are then used to perform complex algorithms which determine the “distance” between closely related genera, tribes or species. The selection of characteristics used has a dramatic impact on the outcome of an analysis. It is virtually unknown for two or more studies to produce identical results. Consequently while there is general agreement about higher level ( superfamily : family ) classification, there are wide differences of opinion about the relationships between various genera, tribes and species.

Genetic interchange

Butterflies can loosely be divided into 3 camps regarding genetic interchange:

The first group comprises species such as the Painted Lady Vanessa cardui, the Small White Pieris rapae and the Pea Blue / Long-tailed Blue Lampides boeticus which are migratory in behaviour and cosmopolitan in distribution. Their nomadic nature brings them into fairly regular contact with distant “cousins” of their own species, so genetic interchange occurs frequently. A Painted Lady in Australia therefore is genetically almost identical to a Painted Lady in Europe, Africa, Asia or North America. Accordingly all races are designated as Vanessa cardui, and there are no recognised subspecies.

The second group comprises of endemics – species which are native to and confined to a limited area such as a particular island or mountain range.

Examples include Calisto confusa which is found only in Haiti; Baronia brevicornis, found only in deciduous scrub forests of s.w. Mexico; Eresia sticta which is restricted to Costa Rica; and Henotesia comorensis – a butterfly confined to the Comoro Islands north-west of Madagascar. By definition endemics have no other races of their own species with which they can interbreed, so there are no subspecies.

The vast majority of butterfly species fall into the third group, which comprises those species which are quite widespread in distribution, but whose populations, due to changes in climate or vegetation have become isolated from each other for hundreds or thousands of years.

Such populations have little opportunity to interbreed, so genetic interchange is minimal, and accordingly each isolated population develops its own characteristics. The Scottish race of the Large Heath e.g. lacks ocelli on the wings and is known as Coenonympha tullia scotica, while the race from Bosnia-Herzegovina has very prominent ocelli, and is recognised as a different subspecies Coenonympha tullia lorkovici.

The subspecies phenomenon is particularly prevalent in South America, where areas of rainforest have during several periods of the Earth’s climatic history become isolated as a result of glaciation or desertification.

The result of this long term separation of populations is particularly noticeable in the genus Heliconius. In the case of Heliconius erato there are no less than 29 subspecies, each with a different pattern. Each subspecies of erato corresponds in colour and pattern with one of the 29 subspecies of another Heliconius species – H.melpomene.

If populations have been isolated for several millennia the differences between them can be very pronounced – patterns, colours, size, and even the shape of the wings can be different, particularly if the races evolve in different habitats and climates.

Sometimes, due to the periodic contraction and expansion of forested areas, subspecies which have been isolated for many thousands of years can be reunited, so that their ranges of distribution overlap.

Thus it is possible, and in fact not uncommon, to find more than one subspecies occurring in the same area of forest.

By definition, all subspecies of any given species are physically capable of interbreeding and can produce fertile offspring. Although such interbreeding may not necessarily occur naturally, it can be induced in captivity.

Some evolutionists argue that if a subspecies becomes isolated for a long enough period of time, it will ultimately evolve structural differences ( e.g. in the genitalia ) that make it physically impossible for it to interbreed with other subspecies, and that if and when this occurs the 2 forms have become sufficiently different for them to be reclassified as separate species, i.e. the evolution of a new species will have occurred.

Others argue that DNA analysis of various subspecies on remote islands in Melanesia indicates that when populations become isolated, inbreeding and genetic entropy occurs, which is contradictory to most theories of evolution, which state that as species evolve they advance – thereby increasing rather than decreasing the number of chemical base pairs in their genome.

The strange creature below is a longhorn caddis fly Mystacides azurea from England. The ‘pincers’ are highly modified palpi which are used to grip and manipulate the female prior to mating. Caddis flies are the ancient ancestors of butterflies and moths. Their larvae are aquatic and live in portable cases constructed from sand grains or fragments of stems bonded to a silk tube surrounding their body. Modern day bagworm moths ( Psychidae ) still have larvae which live inside cases.

The fossil record

The first insects appeared on Earth about 300 million years ago. The earliest Lepidoptera evolved from the Trichoptera ( caddis flies ) about 140-200 mya, coinciding with the appearance of the first flowering plants. The fossilised butterfly Prodryas persephone ( Nymphalidae ) was found in the Florissant beds, Colorado, USA and dates from the Oligocene period, 30mya.

Where & when did the first butterflies appear ?

Long ago the land masses of the Earth were divided into 4 continents – Laurentia, Baltica, Siberia and Gondwanaland. They gradually converged, and about 350 mya became linked, forming the super-continent Pangaea. It seems probable that the earliest butterflies originated on Pangaea, which then began to break up about 130 mya, ultimately forming the present day continents. This may partly explain why all the butterfly families are represented on more than one continent.

A few subfamilies, and many tribes, are limited in their global distribution – the Ithomiini e.g. are found only in the neotropics, and the Tellervini only in the Australian ( Papuan ) region. It seems likely that the latter evolved from their alleged parent subfamily Danainae, AFTER the break-up of Pangaea. However, it is important to realise that the break-up was very gradual, and it is quite possible that all subfamilies and genera may have come into existence at a time when the new continents were still partially linked.

Evolutionary Theory

The philosopher Aristotle ( 384-322 BC ) believed in spontaneous generation – the notion that all living things arose from non-living sources. This probably reflected unexplained phenomena such as swarms of flies apparently being generated spontaneously from dead carcasses. This in turn may have led to religious concepts of reincarnation, resurrection and the ‘soul’. St Thomas Aquinas even concluded that the spontaneous generation of insects was the work of the devil!

The notion of evolution was first mooted by the French biologist Jean-Baptiste Lamarck in 1800. He believed that animal anatomy and behaviour were not fixed, but adapted to circumstances. Lamarck considered that these adaptations could be transmitted to new generations. He believed evolution was driven by 2 forces – one which drove animals from simple to complex forms, and another that adapted animals to local environments and differentiated them from each other.

Darwin’s Theory of Evolution

Charles Darwin went further when in 1859 he published ‘The Origin of Species’ which theorised that all animals evolved by a process of natural selection from more basic life forms. After considerable initial opposition the scientific world accepted and expanded these theories, concluding that life began billions of years ago when viruses, bacteria or similar ‘primitive’ entities somehow arose in the ‘primordial soup’ of early oceans. Put simply, the theory states that adaptations or traits occur naturally in a percentage of a population due to mutation. Evolution occurs as the more successful adaptations become dominant, and former traits are bred out by the natural selection process.

Speciation

Environmental conditions change over a period of time, during which the less adaptable life forms become extinct. Others acquire, via the birth of mutant offspring, new properties that make them more capable of surviving. These traits can be transmitted genetically to future generations, as demonstrated by Mendel’s experiments with hybridisation in the late 19th century.

Most theorists believe that new species probably evolve when the habitat of the ancestral species undergoes major changes. Only those mutations that are able to survive these changes can pass on their genes to future generations. The ancestral form often becomes extinct, and the new form evolves over a period of time, eventually becoming so different from its ancestor that it is regarded as a new species.

Evolution does not however necessarily require extinction of the ancestral species. Natural barriers can emerge such as wide rivers, deserts or mountain ranges, which isolate populations of a given species from each other. In isolation the natural variation which exists in any population will ensue that new traits arise in both populations. One type of biological or behavioural trait may work best in population A, while a very different adaptation may work better in the environment occupied by population B. Thus, provided that their ranges do not overlap, two ‘subspecies’ will evolve.

The figure below illustrates how an emerging mountain range can split a butterfly population. The environment of one population remains largely unchanged, but the other population is subjected to a much drier climate in the rain-shadow of the mountain. In the latter population, only the variants( mutations)  that are best suited to the new environment will survive and pass on their genes to the next generation. A process of natural selection ‘survival of the fittest’ will slowly bring about the evolution of a new species.

Speciation Frequency

There are several factors affecting the rate at which speciation occurs. It is likely to happen more frequently at habitat boundaries, where an existing species has to adapt it’s biology and behaviour in order to survive on different foodplants or in different habitats.

It will also be more frequent in tropical habitats than in temperate regions, because there will be more generations during any given time period. In subarctic regions many species take 2 years to complete their lifecycle. The moth Gynaephora groenlandica spends up to 14 years as a larva!

Most butterflies in temperate North America and Europe produce one or two generations each year. In the tropics however there can be 10 or more generations in the same period. The entire lifecycle of one common tropical butterfly Hypolimnas misippus takes only 23 days to complete.

The more generations there are in a year, the more chances there are for random mutations to occur, and the more opportunities there are for speciation. It has been mathematically calculated that complete substitution of a gene under a natural selection rate of only 1% takes less than 4000 generations. In the case of a species like Heliconius erato, which produces 10 generations a year it it quite feasible then for speciation to occur at intervals of just 400 years.

Is the ‘subspecies’ a valid taxon?

Subspecies are really nothing more than convenience names given to geographically isolated races which have adapted to various environments and evolved new anatomical / behavioural traits that improve their survival rate. These races are capable of interbreeding and producing fertile offspring if brought together in a laboratory. They do not normally interbreed in the wild due to geographical separation, but there are many cases particularly in Amazonia where subspecies have been able to expand their range to the point where they overlap and interbreed with another subspecies.

Examples of subspecies include Papilio machaon brittanicus which is widely distributed throughout the Holarctic region but in Britain is restricted to the Norfolk Broads; and Hipparchia semele thyone and Plebejus argus caernensis, both of which occur across much of the Holarctic including Britain, although these particular subspecies are restricted to a tiny area in north Wales.

Most biologists regard the species as the terminal taxon, with the subspecies being a stepping stone, a transitional taxon which is part of the process of speciation. They consider that subspecies in time will theoretically evolve into new species, replacing, or in some cases existing alongside the ancestor species.

The phylogenetic tree below indicates that the first insects probably branched off as an evolutionary offshoot from other arthropods ( joint-legged animals with an exoskeleton ) about 500 million years ago. The first Lepidoptera ( butterflies, skippers & moths ) and Trichoptera ( caddisflies ) branched from this offshoot about 200 mya.

The table below indicates the presumed evolutionary relationship between butterflies, skippers and the various moth families. The suborders and families at the top of the table are generally regarded as representing the more primitive Lepidoptera, while those at the bottom are the more advanced and specialised. It can be seen that butterflies are supposedly more “advanced” than most moths, but that there are many moth families that are considered to have evolved after the butterflies.

The section dealing with butterflies, skippers and butterfly-moths has been expanded to show the constituent subfamilies and tribes. Some families have not been sufficiently studied to enable them to be split into subfamilies. Likewise certain members of some subfamilies have not been studied well enough for them to be assigned to existing tribes – these are categorised under the heading Incertae-sedis – meaning ‘of uncertain placement’.

*Recent taxonomic revision has resulted in the former families Arctiidae and Lymantriidae being
 reclassified as subfamilies of the Erebidae, as shown in the above table.

The following table lists the number of known species in every butterfly family and subfamily found in each of the world’s 5 zoogeographical regions as indicated above.

The totals are distorted because taxonomists often disagree about whether any particular taxon is a full species or just a subspecies or form. 

Estimates of the total number of known butterfly species therefore vary between 17,000-19,000. The true total will never be known because many will have become extinct even before they are discovered.

Taxonomists however estimate that at least 1100 more species await discovery in the neotropical region alone! It is forecast that another 50 will be discovered in the Holarctic, 150 in the Oriental region, another 50 in Papua New Guinea and West Irian and at least 250 more species in Africa.

If you include moths the total increases tenfold to 174,240 currently known species. The number of undiscovered moths is proportionately much greater than with butterflies however, as a very high percentage of moths are very small with sombre patterns and are extremely difficult to distinguish from each other without the aid of microscopic examination and DNA analysis. The total number of Lepidoptera species probably exceeds 300,000 worldwide.

Data collated by Hoskins from sources including Tolman 1997, Larsen 2005, Lamas 2004, d’Abrera 2001, Scott 1992, Preston-Mafham 1988, McCubbin 1971, Eliot/Corbet & Pendlebury 1992, Shields 1989, Ackery 1995, funet 2014, BoldSystems 2014, LepIndex 2014.

Before the advent of scientific nomenclature, confusion reigned :

Example 1 – The butterfly known in Britain as the Camberwell Beauty has in past times been called the Grand Surprise, the Willow Beauty and the White Petticoat. In the USA it is called the Mourning Cloak. In Europe it has common names in several different languages.

Example 2 – The two butterflies known to early entomologists as the Selvedged Heath Eye and the Golden Heath Eye were later discovered to be the male and female of a single species which was initially called the Gatekeeper but is now called the Small Heath. The original name Gatekeeper is now applied to an entirely different species which has variously been known as the Hedge Brown, Hedge Eye and Large Heath. The name Large Heath however is now used for an entirely different species that was previously known as the Manchester Argus, or Marsh Ringlet !

The Swedish naturalist Carl von Linnaeus ( Carolus Linnaeus ) decided to put an end to this confusion. He realised that an internationally recognised name was needed for every creature and plant, and that every organism should be classified according to it’s relationship with other organisms. In 1735 he launched the Systema Naturae, a catalogue of the names of all known animals and plants. Later, in 1758 came the 10th edition of Systema Naturae, which is regarded as the starting point for the current system of classifying animals and plants by family, genus and species.

Originally Linnaeus placed all butterflies and moths in the same genus Papilio. Later it was realised that there was a need to divide this genus, so as to distinguish groups with different characteristics. Since the time of Linnaeus many thousands of new species have been discovered and described by scientists, and hundreds of genera have been created to accommodate them.

Every known taxon is designated a binomial ( two-word ) name derived from Latin or Greek roots. An example is the Common Blue butterfly Polyommatus icarus :

The Common Blue was designated by Rottemburg in 1775 as Polyommatus icarus. The first part of the name means ‘many spotted’. It refers to the distinctive markings on the underside of the wings of all species in the genus Polyommatus. The name icarus refers to a character in Greek Mythology. According to legend Icarus and his father Daedalus were imprisoned in the Labyrinth with a terrible creature, the Minotaur. In order to escape, Daedalus fashioned a pair of wings for himself and his son, made of feathers and wax. Before they took off from the prison, Daedalus warned his son not to fly too close to the sun. Icarus unfortunately became so overcome by the excitement of being able to fly that he forgot his father’s warning. He got too close to the sun and his wings melted. He then fell into the sea in the area which now bears his name, the Icarian Sea near Icaria, an island southwest of Samos.

Scientific names should always be written with the genus, species and subspecies italicised, then the author’s name and the date the description of the taxon was first published.

Thus the Common Blue is called : Polyommatus icarus icarus ROTTEMBURG, 1775

The taxonomic hierarchy

The Linnaean System divides the Animal Kingdom into groups called phyla. The phylum Arthropoda i.e. those animals with jointed limbs and a hard exoskeleton, is divided into several classes. Among these are the Crustacea which includes crabs, lobsters, shrimps & woodlice. Other classes include Chilopoda ( centipedes ), Diplopoda ( millipedes ), Arachnida ( mites, spiders & scorpions ) and the Insecta ( insects ).

The class Insecta includes over 75% of all animal species. It is divided into several super-orders, one of which is Amphiesmenoptera.

The latter is split into 2 orders – Trichoptera ( caddisflies ) and Lepidoptera ( butterflies & moths ). These 2 orders share a common ancestor, Necrotaulidae, and have many features in common, e.g. their wing venation is fundamentally similar, their wings are covered in setae ( modified to form scales in Lepidoptera ), and their larvae have mouthparts with structures and glands modified to produce silk.

The table below shows Polyommatus icarus in relation to the rest of the Animal Kingdom :

Lepidoptera

About 7% of all life forms on Earth are members of the Order Lepidoptera – the butterflies, skippers and moths ( indicated in orange ) :

The Lepidoptera comprises of about 174,250 known species ( this only represents a fraction of the species in existence, as many more await to be discovered and described, especially among the tropical “micro” moth families ). The classification of Lepidoptera is under constant revision, but they are currently divided into 126 families, 7 of which are colloquially known as butterflies :

Butterflies by day and moths by night ?

It is wrong to think of butterflies and moths as being different. The families which we call butterflies are generally those with brightly coloured day-flying species. There are however hundreds of moths among the families Zygaenidae, Arctiidae and Uraniidae which are also brightly coloured and day-flying. Conversely there are many butterflies among the Hesperiidae, Satyrinae and Brassolini that are very dull and inconspicuous, and would be dismissed as moths by most people.

Another “fact” often quoted is that butterflies always have clubbed tips to their antennae, but that moths never do. The colourful day-flying Zygaenidae moths however do have swollen tips to their antennae, and the huge day-flying Cane-borer moths ( Castniidae ) possess clubbed antennae just like those of butterflies!

Perhaps even more surprising is the fact that many butterflies fly at night as well as during the day, particularly in the tropics. Examples include the Caligo Owl butterflies, Melanitis Evening Browns and certain Riodinids. Examples from temperate regions include the Red Admiral Vanessa atalanta and the Monarch Danaus plexippus both of which regularly fly into moth traps in the middle of the night.

The 35 species of the family Hedylidae are nocturnal and moth-like in appearance. The early stages however have many butterfly-like characteristics. The eggs for example are structurally closer to those of Pieridae and Nymphalidae than to moth eggs. The caterpillars have horn-like processes like Apaturinae, a bifid tail as found in Satyrinae, and secondary setae as found in Pieridae. They also have an “anal comb” used for expelling droppings – a characteristic of the Hesperiinae. The pupae likewise have structural characteristics more representative of butterfly pupae, and are secured to the substrate with a silken girdle, just like those of the Pieridae and Papilionidae.

Taxonomic revision

Taxonomy is not an exact science. It relies on suppositions about the relationships between various species, and about their evolutionary ancestry. Because of this, the classification ( and the scientific names ) of butterflies and moths are under constant revision.

New techniques such as microbiology, phylogenetics, DNA sequencing, and the study of larval morphology regularly shed new light on the relationships between species. This increasing knowledge regularly results in the necessity to revise classification. Sometimes it is a simple matter of relocating a species to a different genus. On rare occasions however it may require that a genus, tribe or even an entire subfamily be migrated from its familiar home and relocated into another family or superfamily.

The inexact nature of taxonomy, and the fact that it relies on opinion rather than fact, unfortunately means that scientists often find themselves in disagreement about which genus a particular species belongs to, or whether two or more butterflies with very similar characteristics should be classified as separate species or as subspecies.

Occasionally a taxonomist will believe that he or she has discovered a “new to science” species and will describe it’s characteristics and publish a name for it. Later however they may realise that the species has already been described and named by someone else. In such cases the oldest name takes precedence, and the newer name is discarded, and listed as an invalid ( junior ) synonym.

How scientists describe and name new species

When someone thinks they’ve discovered a new species, they have to provide sample specimens to taxonomists for analysis. By comparing the structure of the wing venation, genitalia and various other anatomical features to that of currently known species, taxonomists can then easily ascertain the genus, and decide whether the specimens represent a previously known species or a new one.

If there are significant differences between the new species and all previously known species it may be regarded as sufficiently unique to deserve the creation of a new genus. If on the other hand its anatomy is close to that of other species it will be placed in an existing genus, and will be allocated a new species name in recognition of its uniqueness.

New species are given a Latinised name and a full scientific description, which are published in a recognised scientific journal.

The origin of scientific names varies enormously. Some species are named after Greek gods, some are named after the place where the butterfly was discovered or named in honour of some eminent entomologist. Names can also be descriptive of the colour, pattern or wing shape.

The Charismatic Metalmarks

Taxonomists are not usually renowned for having a great sense of humour, but amongst their more hilarious moments they have colluded to provide us with some entertaining scientific names. Hence there are a pair of metalmarks from Colombia, named by Hall & Harvey in 2002 as Charis ma and Charis matic. Both have now been renamed rather less attractively as Detritivora ma and D. matic. The new genus name refers to the fact that the larvae feed on decaying leaves and other detritus on the forest floor.

The world’s most dismal butterfly ?

Sometimes it can be difficult to think up names for some of the more mundane looking species, particularly for the hundreds of near-identical dull brown skipper species found in the neotropics. In 1997 Austin was apparently so totally unimpressed with his latest discovery that he gave a new Mexican species the unfortunate name Inglorius mediocris, which needs little translation !Below is an example of a scientific description :

More ‘creative’ species names

The entomologist Burns was clearly having a mental block when it came to naming his new skipper – Cephise nuspesez ( pronounced “new species” ). Just to prove that weird humour is not confined to entomologists, here are some of the equally odd scientific names given to other creatures :

The above show both creativity and humor, but in 1969 when Spencer had the task of inventing names for new flies, he invented possibly the most boring series of species names in existence, by naming his discoveries sequentially, as **Ophiomyia prima,** **secunda,** **tertia,** **quarta,** **quinta,** **sexta,** **septima,** **octava,** **nona,** **undecima,** and **duodecima** (Latin for “first,” “second,” “third,” etc.). Dybowski went to the opposite extreme when he proposed the ludicrously unpronounceable name **Gammaracanthuskytodermogammarus loricatobaicalensis** for a new Amphipod in 1927. It would have been the world’s longest scientific name, but luckily common sense prevailed and the name was rejected by the International Commission for Zoological Nomenclature. The honor of having the longest scientific name actually approved by the ICZN goes to a species of Stratiomyid fly – Parastratiosphecomyia stratiosphecomyioides.

The shortest appears to be that of a Vespertilionid bat – Ia io, although there is a thrip with a single-letter species name – Plesiothrips o !