Genus: Thecla

Family:LycaenidaeLeach, 1815
Subfamily:TheclinaeButler, 1869
Tribe:ThecliniSwainson, 1831
Genus:TheclaFabricius, 1807
Type Species:betulae(Linnaeus, 1758)

Description

Family: Lycaenidae

The Lycaenidae is a family comprising several thousand species, the majority of which are small in size and with a rapid flight. Many are brilliantly coloured, and this is often the result of interference effects caused by the microstructure of the wings.

Eyes may be smooth or hairy, often with a border of dense white scales. Labial palps usually protrude forward, or are slightly ascending. Antennae are half the length of the forewing or slightly shorter, with a variable but usually long club. All legs are fully functional in both sexes, although the forelegs of the male are less well developed, and smaller, than in the female. All legs have a pair of claws, with the exception of the male foreleg which has a single claw. In some genera there are spines on the tibia.

The number of veins on the forewing is generally reduced to 11 or even 10 with vein 8 and possibly vein 9 absent. The cell is narrow when compared with other families. The undersides of the wings typically differ greatly from the uppersides, often consisting of a pattern of spots. Sexual dimorphism is usually well-defined. In some genera there is a short tail at vein 2 of the hindwing. Androconial scales are usually present on upper side of male forewing.

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Common Blue (Polyommatus icarus)
Photo © Timothy Freed, whose original drawing is shown in Moths and Butterflies of Great Britain and Ireland, Volume 7, Issue 1 (Emmet & Heath, 1989)

Eggs are disc-shaped and covered in a network of ribs and hollows. The larva is shaped like a woodlouse and is covered in short hair. It has a retractable neck that, in some species, is pushed forward as the larva scoops out the content of a seed pod or leaf on which it is feeding. In early instars the larva may enter a seed pod or leaf to feed. Pupae are stout and may be attached to the foodplant or other vegetation by a rudimentary silken girdle and the cremaster, but may equally be found lying free among vegetation or on, or below, the ground.

This family has developed a close associated with ants. In many species the larva has a specialised "honey gland", known as the Newcomer's gland, on the 7th abdominal segment, that is usually developed in the 2nd instar. This gland exudes a sweet cocktail of amino acids that is attractive to ants, which, in turn, offer the larva a level of protection. Ants can also be found tending to pupae and accompaning adults during their emergence. The association is most specialised in the Large Blue (Maculinea arion) where the late-instar larvae feed on ant grubs, and the pupa is formed within the ant nest.

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Holly Blue (Celastrina argiolus)
Larva with ant in attendance

Photo © Peter Eeles

Silver-studded Blue (Plebejus argus)
Newly-emerged adult

Photo © Iain Leach

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Large Blue (Maculinea arion)
Larva being "milked"

Photo © Marcin Sielezniew

Large Blue (Maculinea arion)
Pupae in ant nest

Photo © Marcin Sielezniew

Subfamily: Theclinae

Description to be completed.

Tribe: Theclini

Description to be completed.

Genus: Thecla

Description to be completed.

The Butterflies and Moths of the World project, run by the British Museum of Natural History, has completed a detailed analysis of various genera and their type species. Click here to visit the relevant page for this genus.

Species

This genus is represented by the species shown below.

Brown Hairstreak, Steyning Coombe, Sussex 19-Aug-2015

Brown Hairstreak
Thecla betulae
Photo © Neil Hulme