Vanishing Species – Butterflies & Moths


An article by Mohan Pai

Lepidoptera

 

Butterflies & Moths

Malabar Banded Swallowtail

The metamorphosis from caterpillar to pupa to butterfly remains one of the most enigmatic feats of nature.

 

Butterflies and moths belong to the order Lepidoptera which is a Greek word for ‘scales’ and ‘wing’, the most obvious feature that separates them from other order of insects is their scaled wings. There are around 1,60,000 different known species of butterfly and moth across all corners of the globe and only 10 per cent of these are butterflies. They can survive in an incredibly diverse range of habitats, from frozen Arctic tundra to high-altitude mountain slopes to humid rainforests. It is perhaps this diversity and adaptability that has enabled the Lepidoptera to survive on the planet for the last 140 million years. The first Lepidoptera were primitive moths and butterflies evolved around 40 million years ago. Butterflies and moths are members of the insect class, sharing the same key features of three pairs of legs and three body parts: head, thorax and abdomen. In addition to these features, Lepidoptera also have two pairs of wings, the forewings and hindwings, which are covered with scales. These scales reflect light, revealing the colours and patterns that are so important when identifying species. The pair of antennae on the head of the butterfly is the primary sense organ, receiving smells, pheromones and vibrations. A butterfly’s proboscis is its tongue, enabling it to suck up food, nutrients and moisture. It is hollow and contains two parallel tubes; the end bears the taste sensors. Different species will have different lengths of proboscis: some members of the hawk moth family have proboscis that exceeds their own body length and is capable of piercing fruit or beehives, whereas others such as the luna moths, have no mouth parts at all and cannot feed as adults. Another organ is the labial palps, used to clean the proboscis and eyes and to sense and taste food. The head also bears a pair of compound eyes, capable of detecting colour and movement. The jointed legs contain sensors at the ‘feet’ which enable butterfly to identify the plant it has just landed on, particularly important for females that need to lay eggs on a specific host plant. Probably the first point of observation when identifying a butterfly or moth is the colour and patterning that is displayed on its wings. When a butterfly is in flight this can be particularly difficult to do; it is when at rest that we get the opportunity to closely examine markings of a particular species. The majority of butterflies hold their wings closed above their bodies, leaving only the underside visible; some will hold their wings out flat, perhaps sunning themselves, affording us a glimpse of their brightly coloured upper side.

Butterfly or Moth ?

In some respects the differences between butterflies and moths may seem rather arbitrary. Although moths are regarded as butterflies’ less colourful, less attractive cousins, there are great many highly coloured daytime-flying moths.

The Atlas moth -world’s largest moth.

Conversely, a large number of butterflies can appear rather dull and insignificant, and are often mistaken for moths. There are, however, a number of general features that separate moths from butterflies. Butterflies are diurnal – daytime – fliers, whereas the great majority of moths are nocturnal, flying and (if appropriate) feeding at night. They also differ structurally; when resting, the wings of butterflies are usually held together upwards over the back of the body, where as moths will fold their wings flat across the body, the hindwing tucked beneath the forewing. In flight, the wings of the moth are ‘coupled’ together with the use of special bristles on the hindwing which catch hold of the forewing, Butterflies lack this feature; instead their hindwing is expanded underneath the forewing, providing support with which to fly. The antennae of each also differ; butterflies have very slender antennae which are clubbed at the end; moths lack this clubbing, having either slim or feathered antennae.
Luna Moth

Butterflies also tend to have more slender bodies, whereas some moths can be very stocky and broad in shape .There are, of course, exceptions to all these rules: the colourful daytime moths of the Uranidae family and the Australian Regent Skipper butterfly with its moth-like wing-coupling device are just two examples among many.

Life-cycle

There are four stages in the life-cycle of all Lepidopteras – egg, caterpillar, pupa and butterfly – and each stage is vital. Butterflies are not simply attractive pollinators of Garden flowers; their ultimate goal is to mate and successfully reproduce; likewise, caterpillars must not only feed and store up energy, they also have to ensure that they are not the victims of hungry predators. Laid singly, in small groups or in huge numbers, eggs can take either a few days or several weeks to hatch. They can be one of a number of shapes, colours and even sizes; some eggs are tiny, others surprisingly large. Eggs are usually laid on specific host plants by the female butterfly, which walks across the plant surface using the sensors in her legs to determine it is the correct one. Less fussy eggs can be released in flight, particularly those whose caterpillars feed upon grass. Once the egg hatches, the newly emerged caterpillar begins by eating the hard shell, then it gets to work eating its host plant. Caterpillars also appear in a wide variety of sizes, shapes and colours. They are particularly vulnerable to predatory birds, other insects and lizards are among the many animals that prey on these butterfly larvae, and so there appearance is often determined by their need to protect themselves. Poisonous caterpillars may appear brightly coloured to ward off attack, or bear aggressive spines that can irritate if touched or ingested. The caterpillars of the Arctid moth family are particularly hairy and collectively referred to as ‘wooly bears’. Some caterpillars display very unusual and somewhat aggressive features, such as horns, alarming tail whips and false eyespots. Many Swallowtail caterpillars have an organ called an osmatarium, rather like an inflatable horn, which releases a repulsive scent. The caterpillars of the Puss moth has a number of these aggressive attributes, and can also spit formic acid for good measure. Many other caterpillars adopt rather more passive but equally successful methods of protecting themselves from predators, either adopting camouflage or simply hiding within or beneath the foliage. Caterpillars spend most of their time eating, and as their bodies grow they slough off their skin, rather like a snake. Most caterpillars will shed their skin several times before they are large enough to begin pupating. For most species, this means that the final skin-shedding reveals not another caterpillar but its chrysalis or cocoon. For others, particularly moths, the chrysalis is spun from single strand of silk, encasing the caterpillar in a protective shell so that it can begin its transformation. Once the caterpillar has revealed or spun its chrysalis, it enters the pupa stage. As a pupa, it is extremely vulnerable to predators since it is completely immobile; consequently pupae will adopt a number of strategies to protect themselves. Most pupae are incredibly well camouflaged, resembling dry leaves, twigs, fresh buds or even bird droppings such as those of the Swallowtail family. Some pupa casings are covered with spines while others containing a poisonous butterfly will advertise their inedible status. Many species pupate underground, within plant roots or even inside ants’ nests, such as the Large Blue butterfly pupa. It usually takes around two weeks for pupation to complete, although some species can take longer – several moths, or even two years, depending on external circumstances.

Owl Butterfly

Behaviour 

The lifespan of a butterfly varies from species to species. Some live for less than a week, others long enough to migrate through the winter months. But the typical adult butterfly will, during its lifetime, fly, feed, mate and migrate.Feeding butterflies use their probocis to suck up liquid nutrients such as flower nectar, tree sap, rotten fruit juices, honeydew, blood and faecal liquid and even in some cases, animal tears. Some male butterflies, such as the Blue Triangle, will feed from the mud found in puddles or on riverbanks, probably seeking extra nutrients necessary for reproduction.Reproduction can only take place when butterflies of the same species successfully identify one another. This can be particularly tricky when different species look similar or when environment makes it awkward to spot a potential mate. Some butterflies are dependent upon phenomones or scent to entice their partners, others will engage in elaborate courtship displays which communicate compatibility as well as general suitability. Mating pairs will clasp together, either landed or in air, and can remain attached for anything from twenty minute to twenty-four hours. The male then usually heads off in search of a new mate while the female begins to search for a suitable place to deposit her eggs.

Habitat

The relationship between butterflies and their habitat is crucial; particular habitats are chosen by individual species because they have evolved adaptations suitable to those habitats.All Lepidoptera need warmth to provide them with the energy to fly; therefore butterflies are found in sunny, tropical and temperate regions. They will need specific foods both for breeding and for the adults to feed. Typical habitats will therefore be places such as open woodlands, where the sunlight can penetrate and where there are plentiful flowers, or meadows and grassland, heathland and coasts with their specific flora, or mountain slopes. Powerful butterflies will survive in forest or woodland canopies, living up at the treetops; weak fliers prefer to stay closer to the ground amongst shrubs and trees which will provide protection from winds. Butterflies found in woodland will often be coloured red, brown or grey, so they resemble dry leaves or bark; others are bright green, like fresh leaves. Butterflies are dependent upon these particular places, and the loss of native habitats can only have dire consequences for their numbers.With so many potential predators, butterflies and moths employ a number of techniques to aid survival. Many species are inedible, their caterpillars feed fro host plants that contain poisons, storing these in their bodies so that the adult butterfly can benefit from the chemicals. Poisonous butterflies advertise the fact to birds, lizards and other insects with their brightly coloured and patterned wings. Many edible butterflies take advantage of these poisonous species by copying their appearance; this technique is known as mimicry. Butterfly will mimic others for one of two reasons; either to appear to be poisonous when not, as does the non-poisonous mimic of the Monarch, the Viceroy, or to emphsize their own poisonous status.Edible species that do not mimic use other tactics. Many will adopt camouflage as an effective technique to avoid becoming prey; the Indian Leaf butterfly is an excellent example of this, as are a number of moths, including the Brindled Beauty.

Mud puddling – Indian Swallowtails

Others will use their wing markings to confuse or frighten predators. Distinctive markings suggest an even larger predator at hand; the owl face seen by the enemy is simply the wings of the Owl butterfly, the snake’s head among the leaves is actually the hooked forewing of the Atlas moth. Eyespots are particularly effective way of confusing and warding off enemies; Some butterflies, such as the Blue Morpho, have a solid colour on their upper side but large eyespots from below which startle a predator when they are flashed unexpectedly. Butterflies that use eyespots to frighten their enemies, such as the Peacock, can often find themselves with ragged wings as a result of inquisitive pecks from confused birds. Although dangerous, these pecks warn the Peacock of danger, giving it time to fly away.

The Big and the Small Butterflies

Butterflies come in various sizes. The smaller Blues are no larger than afingernail and the largest Swallowtail is larger than the smallest birds. The timiest butterfly in the world are the Grass Jewel (wingspan 15-22 mm) and the Tiny Grass Blue (wingspan 16-22 mm). Both these butterflies occur in peninsular India. The world’s largest butterfly, Queen Alexandras’s Birdwing, Ornithoptera alexandrae measures about 250 mm between its wingtips. Among the Indian butterflies, Southern Birdwing is the largest with a wingspan of 140-190 mm.


Conservation

With such a large number of of different species of butterfly and moth in existence, it is hard to believe that they are seriously threatened. However, a number of fascinating and beautiful butterflies are in peril, from either habitat change or over zealous collectors. Loss of native habitats is the most serious threat. On a large scale, massive deforestation, such as in Central America and Asia, is affecting many different species. However, even on a small scale, many butterflies rely on plants that we consider weeds, such as nettles, thistles or dandelions. The use of pesticides can have a harmful effect on some species, and pesticides that target destructive butterflies, such as the Gypsy moth, are also responsible for the near-eradication of other, innocent species. There are some conservation measures in place: many species are legally protected from collectors; others have been reintroduced into native environments. However, many butterflies and moths remain under threat of extinction.

Indian Butterfly Families
The Swallowtails Papilionidae

T
he swallowtail butterfly family, consists of about 550 species of which 84 are found in India. Most swallowtails are large, brilliantly coloured and extremely beautiful.

Butterflies from this family are commonly found in both tropical and temperate habitats.


The Brush-footed Butterflies

The Brush-footed family is the largest butterfly family in the world, consisting of several thousand species. The butterflies are medium to large sized and can be extremely diverse in nature. In India there are about 480 species from this family. This family includes the subfamily Danainae, the milkweed butterflies.


The Whites and Yellows

Butterflies from this family are predominantly White or Yellow in colour along with black markings.Their flight is rapid and they move erratically from plant to plant. 81 Species from this family are found in India.

The Metalmarks
The metalmark butterflies get their name from the small metallic looking spots that are commonly found on their wings. In India these butterflies are commonly known as the Punches & Judies. There are about 1000 species of metalmark butterflies worldwide of which only 16 are found in India.

The Gossamer-Winged Butterflies

Butterflies of this family are small, mostly under 5 cm. Their flight is rapid and erratic and very close to the ground. Subfamilies include The Blues, Coppers, Hairstreaks and Harverstes.

The Skipper Butterflies

A family of generally small butterflies with short stout bodies and a characteristic rapid, skipping flight. They actively feed on flower nectar and most species have proboscises that are much longer than butterflies of any other family. Skippers are very difficult to identify in the field and require close examination and study for specie level identification.

Acknowledgement: ‘A Concise Guide to Butterflies & Moths’ by Elizabeth Balmer, ‘Butterfles of Peninsular India’ by Krushnamegh Kunte, Nerdybirders.com
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