Large blue butterfly
The Large Blue is a blue butterfly
A butterfly is a mainly day-flying insect of the order Lepidoptera, which includes the butterflies and moths. Like other holometabolous insects, the butterfly's life cycle consists of four parts: egg, larva, pupa and adult. Most species are diurnal. Butterflies have large, often brightly coloured...

, that is resident in Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

 and some parts of Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

. The butterfly was became extinct in the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 in 1979, but has since been reintroduced by conservationists. Conservation efforts have, until recently, been hindered by very limited knowledge of the butterfly's complicated life cycle. Uncommon throughout its range, the Large Blue Butterfly primarily resides in heaths
Heath (habitat)
A heath or heathland is a dwarf-shrub habitat found on mainly low quality acidic soils, characterised by open, low growing woody vegetation, often dominated by plants of the Ericaceae. There are some clear differences between heath and moorland...

, sand dunes and hillsides.


Large Blue caterpillar
Caterpillars are the larval form of members of the order Lepidoptera . They are mostly herbivorous in food habit, although some species are insectivorous. Caterpillars are voracious feeders and many of them are considered to be pests in agriculture...

s are about half an inch in length and can live as long as 9 months before they form a chrysalis to become a butterfly
A butterfly is a mainly day-flying insect of the order Lepidoptera, which includes the butterflies and moths. Like other holometabolous insects, the butterfly's life cycle consists of four parts: egg, larva, pupa and adult. Most species are diurnal. Butterflies have large, often brightly coloured...

. Large Blue butterflies have a wingspan of up to 2 inches, and will live for only a few weeks. The wings of the Large blue butterfly are speckled with black dots. Compared to a Large Blue caterpillar, the adult's lifespan is short.


Large Blue caterpillars feed on wild thyme
Thyme is a culinary and medicinal herb of the genus Thymus.-History:Ancient Egyptians used thyme for embalming. The ancient Greeks used it in their baths and burnt it as incense in their temples, believing it was a source of courage...

 or marjoram
Marjoram is a somewhat cold-sensitive perennial herb or undershrub with sweet pine and citrus flavours...

 flowers for the first few days of development. Once well fed, the caterpillar secretes sweet fluids to attract red ants of the species Myrmica sabuleti
Myrmica sabuleti
Myrmica sabuleti is a species of ant. The species is indigenous to Europe and most colonies are polygynous. The Large Blue butterfly caterpillar parasitically prey on the species as it hatchess on thyme buds and then tricks the ants into believing it is one of their own larvae, ants then carry it...

. The ants then take the caterpillar back to their nest and proceed to feed from these secretions. The caterpillar then hibernates
Hibernation is a state of inactivity and metabolic depression in animals, characterized by lower body temperature, slower breathing, and lower metabolic rate. Hibernating animals conserve food, especially during winter when food supplies are limited, tapping energy reserves, body fat, at a slow rate...

 inside the ants' tunnels. On emerging from hibernation, the caterpillars will then begin to eat the red ant's eggs and larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...

e for up to 3 weeks. It will then hang itself by its legs on the nest's roof and build a chrysalis around itself. The caterpillar will spend a further 3 weeks transforming into the Large Blue butterfly adult. After its change from caterpillar to butterfly, the insect emerges from its chrysalis and leaves the red ant nest to find a mate. Usually, red ants will escort the newly emerged butterfly to the surface, taking it to a low plant or shrub nearby. The red ants will encircle the butterfly and ward off any predators that attempt to attack the butterfly as it dries out. After the butterfly is ready to fly away, the ants will retreat back into their nest. In addition to Myrmica sabuleti, there have been instances of the butterfly larvae using Myrmica scabrinodis but with much poorer survival rates. In the UK and in cooler or more mountainous areas in Europe, wild thyme is the food-plant, marjoram being used by populations in warmer areas.

Pregnant Large Blue females will lay their eggs only on wild thyme buds or on the buds of Marjoram, which young caterpillars feed exclusively on until after the third moult, when they are ready to seek out the appropriate ants nest. On sites where Large Blues occur there is usually a high density of appropriate ants nests. When the caterpillar is ready, it will drop itself off the food-plant and wait to be picked up by a passing red ant, which will then carry it to its nest. The red ant strokes the caterpillar with its antenna
Antenna (biology)
Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....

, making the caterpillar produce a small drop of honeydew
Honeydew (secretion)
Honeydew is a sugar-rich sticky liquid, secreted by aphids and some scale insects as they feed on plant sap. When their mouthpart penetrates the phloem, the sugary, high-pressure liquid is forced out of the gut's terminal opening. Honeydew is particularly common as a secretion in the Hemipteran...

. This action is called "milking", which the ant continues to do until the caterpillar raises half of its body into the air. When this happens, the red ant picks the caterpillar up with its jaws and takes it into its nest. Once inside the red ant's nest, the ants will stroke the caterpillars with their antenna. After a while, the Large Blue caterpillar secretes more honeydew on which the red ants and their young feed. Soon after this process is complete, the caterpillar will seek out the nesting chambers and proceed to eat red ant eggs and larvae. When winter draws near, the Large Blue caterpillar begins to hibernate.

Often, the red ant colony will bring in too many Large Blue caterpillars. When this happens, the caterpillars usually eat all the red ant eggs and larvae, thus eliminating the colony. However, with no ant eggs to feed on, the caterpillars starve to death. Another bizarre and unexplainable occurrence is that when the red ant colony produces more than one queen ant, the workers are often sent to attack and eat the caterpillars.

To make itself less of an intruder to the red ants, Large Blue caterpillars will adopt the red ant's scent and mimic the ant's sounds, in addition to providing the ants with honeydew. Once the caterpillar is inside its chrysalis, it will rub its head against the chrysalis walls to make a scraping sound that the red ants make. Failure to complete any of these disguises will often lead to the caterpillar being eaten by the red ants.

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