Large Blue (butterfly)

"Large blue" redirects here. This can also refer to other species of Maculinea.

Large Blue
Upperside
Underside
Conservation status
Near Threatened (IUCN 2.3)
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Lepidoptera
Family:	Lycaenidae
Genus:	Phengaris
Species:	P. arion
Binomial name
Phengaris arion (Linnaeus, 1758)
Synonyms
Papilio arion Linnaeus, 1758 Glaucopsyche arion (Linnaeus, 1758) Maculinea arion (Linnaeus, 1758)

The Large Blue (Phengaris arion, also known as Maculinea arion and Glaucopsyche arion) is a blue butterfly resident in Europe and some parts of Asia. The butterfly became extinct in the United Kingdom 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, sand dunes and hillsides.

Description

Large Blue caterpillars are about half an inch (13 millimeters) in length and can live as long as 9 months before they form a chrysalis to become a butterfly. Large Blue butterflies have a wingspan of up to 2 inches (50.8 millimeters), and will live for only a few weeks. The wings of the Large Blue butterfly are speckled with black dots. Compared with a Large Blue caterpillar, the adult's lifespan is short.

Biology

A Large Blue on Thymus praecox

Large Blue caterpillars feed on wild thyme or marjoram 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. The ants then take the caterpillar back to their nest and proceed to feed from these secretions. The caterpillar then hibernates inside the ants' tunnels. On emerging from hibernation, the caterpillars will then begin to eat the red ant's eggs and larvae 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 on exclusively until after the third moult, when they are ready to seek out the appropriate ant nest. At sites where Large Blues occur, there is usually a high density of appropriate ant 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, making the caterpillar produce a small drop of honeydew. 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 caterpillar with their antennae. 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, eliminating the colony. With no more 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 intrusive to the ants, a Large Blue caterpillar will assume the ants' scent and mimic their sounds. Once the caterpillar is inside its chrysalis, it will rub its head against the chrysalis walls to make a scraping sound similar to the one made by the ants. Failure to adopt any of these measures will often lead to the caterpillar being eaten by the ants.

References

• Reader's Digest, The Wildlife Year, p 190, ISBN 0-276-42012-8.
• Gimenez Dixon (1996). "Maculinea arion". IUCN Red List of Threatened Species. Version 2009.2. International Union for Conservation of Nature. http://www.iucnredlist.org/apps/redlist/details/12659. Retrieved May 9, 2006. 

See also

• List of butterflies of Great Britain

External links

• The life cycle of the Large blue butterfly.
• Indepth information on the Large blue butterfly.
• Butterfly Conservation - Large Blue Project.
• Cornwall Wildlife Trust - Large Blue Reintroduction.