Home

 

 
Butterflies of Britain & Europe
 
Speckled Wood
Pararge aegeria tircis  BUTLER, 1867
Family - NYMPHALIDAE
subfamily - SATYRINAE
Tribe - SATYRINI
subtribe - PARARGINA
 
 introduction | habitats | lifecycle | adult behaviour
 

Speckled Wood Pararge aegeria, female
 
Introduction
 
This common woodland butterfly was originally known in Britain as the Enfield Eye or Wood Argus. The name Speckled Wood first appeared in 1766, in Moses Harris's famous book The Aurelian.
The butterfly is widely distributed in Europe but is absent from the sub-arctic areas of Norway and Sweden. Beyond Europe it occurs in the Atlas mountains of north Africa and extends into Asia as far east as the central Ural mountains.
The British / northern European subspecies tircis is marked with pale creamy spots, but in southern Europe the normal form of the butterfly has the wings patterned with large orange blotches, and can be mistaken for the Wall Brown Lasiommata megera.
There are 2 other very similar Pararge species - xiphiopides which is endemic to the Canary Islands, and xiphia which is endemic to Madeira ( where aegeria also occurs ).

Speckled Wood, male, Pararge aegeria, Powerstock Common, Dorset
 
Habitats
 
It is often stated that butterflies make excellent "indicator" species, as their distribution ranges and population dynamics adjust rapidly in response to changes in the environment. This is particularly true of the Speckled Wood. The butterfly was widespread and fairly common in Britain until the late 19th century when it suffered a sudden and unexplained collapse in numbers. Then from the 1930's onwards it gradually expanded it's range : this species favours darker and damper woodlands than most other butterfly species, so it's populations expanded in response to the large scale conversion of coppiced woodlands to plantation management.
Today the Speckled Wood is regarded as a common woodland butterfly, which breeds in damp areas where dappled sunlight filters through the trees. It can commonly be seen basking on low foliage, or on forest paths in deciduous woodland, but is quite tolerant of shade and can also be found in conifer plantations, where it breeds along grassy rides.
In recent years it has demonstrated a favourable response to climatic change, having expanded into more open habitats, and can regularly be seen in gardens, along hedgerows, and scrubby areas of open grassland. It has also extended it's range northwards, now reaching Ullapool in n.w. Scotland.
 
Lifecycle
 
The Speckled Wood is unique among British species in that it can hibernate as either a caterpillar or chrysalis. Thomas states that "as a rule, caterpillars which experience 12 or more hours of light a day go on to form adults in the same year, whereas those that receive less light either form hibernating pupae, or overwinter as caterpillars".  The consequence of this dual overwintering strategy is that the spring emergence of adults is very protracted. At any given site however the adults tend to emerge in synchrony, suggesting that the hibernation stage is dependent on habitat and local climate.
There is disagreement among entomologists about how many broods occur in various parts of Britain. It certainly produces 3 broods in southern Britain, and Thomson states that there are also 3 broods in Scotland, "where the 3rd brood is partial".
Normally the first adults appear in late March but the emergence is very protracted, extending well into June, overlapping with the second brood, which flies between late June and August. The third brood begins in August at some sites, but not until September at others - and late emerging adults may still be flying as late as mid November. Individuals have a lifespan of between about 7-20 days.
The spherical egg is straw coloured, and finely ribbed. It is laid singly on the underside of grass blades, always where the grasses are growing in dappled light, usually at the base of bushes. It hatches after about a week.
Unlike most other Satyrine larvae, which are generally nocturnal, the caterpillar of the Speckled Wood feeds by daylight. It is pale green, marked with thin longitudinal yellow and whitish stripes, and is perfectly camouflaged at rest on grass blades. It feeds on soft grasses, principally cocksfoot Dactylis glomerata, couch Agropyron repens, wood millet Milium effusum, Yorkshire-fog Holcus lanatus, creeping soft grass Holcus mollis, and wood meadow grass Poa nemoralis.
The chrysalis is formed hanging by the cremaster from woody stems. It is variable in colour, some being pale green, while others can be quite dark, particularly those of the over-wintering brood.

Speckled Wood Pararge aegeria, male, Purbeck Hills, Dorset, England
 
Adult behaviour

 

The Speckled Wood flies in shadier habitats than most other British butterflies, and is commonly active on dull overcast days when other species refuse to fly.

Speckled Wood Pararge aegeria, female, Crab Wood, Hampshire, England

 

On sunny mornings the males take up residence in areas of woodland where dappled sunlight filters through the trees.  Each male selects a "perch" in the form of a sunlit leaf, from which it can survey and intercept passing females. During the course of the morning, the changing position of the sun causes the various perching places to be periodically shaded, at which time each male has to move to establish a new perch. Inevitably this results in a high number of male-male encounters.

When males meet, they engage in a sortie, spiralling up to the tree tops. This appears to be a test of strength, but probably also involves chemical messages. Either way, after a few moments a "winner" emerges to return to his chosen perch. Experiments have shown that the winning male is usually the one which first established his perch. The intruding male is ousted, and has to establish a new perch elsewhere in the vicinity. In experiments when 2 males have been introduced simultaneously into an area, and both believe they have ownership of a perch, the ensuing sortie can continue unabated for several minutes. Ultimately one of the combatants seems to get lost, or gets distracted, leaving the other to reclaim its perch.

Some males adopt a different mate-location strategy, choosing to patrol in search of females. In his fascinating book Butterflies of Britain and Ireland, Jeremy Thomas states that "certain individuals - especially those possessing 4 spots on the upperside of each hindwing, are more inclined to perch, whereas males with 3 spots have a tendency to patrol".

Males always intercept other Speckled Woods of either sex but usually ignore other species. When a receptive female is intercepted, she settles on foliage, and spreads her wings. The male then settles below her, and gently walks onto her hindwings. Butterflies have olfactory sensors on their feet, so this ritualised behaviour probably enables the male to "taste" her scent and determine whether she is recently emerged - vital information because younger females have a longer life ahead of them, and are therefore capable of laying more eggs.

Copulation takes place in the late morning and lasts for about an hour.

The adult butterflies feed mainly on honey dew ( aphid secretions ) on the upper surface of oak, ash or hazel leaves.  The spring and summer adults rarely visit flowers, although I have at times seen them nectaring at wood spurge. In late summer males sometimes nectar at fleabane or knapweed flowers, but are more often seen feeding at the juices oozing from fermenting blackberries. Females prefer to feed on the sticky secretion which coats ash buds - individuals often spend several minutes at a time walking about on ash twigs, avidly feeding on the sticky secretion which coats the buds. They also visit the flowers of certain trees and bushes including pear, hawthorn, lime and buckthorn.

Overnight and in dull, cold or wet weather, the butterflies go to roost in bushes - e.g. at Ballard Down in Dorset I have watched them go to roost in prickly gorse bushes, at Stansted Forest in West Sussex I have seen them roost in bramble bushes, and at Noar Hill in Hampshire I have watched them enter blackthorn and dogwood bushes in late afternoon.

Speckled Wood Pararge aegeria aegeria, male, Andalucia, Spain ( image © Peter Bruce-Jones )
 
 

 

Contact  /  About me

Butterfly-watching holidays

Trip reports

UK latest sightings

Frequently asked questions

Strange but true !

Taxonomy & Evolution

Anatomy

Lifecycle

Enemies of butterflies

Survival strategies

Migration & dispersal

Habitats - UK / Palaearctic

Habitats - Tropical rainforests

Butterfly world census

Butterflies of the World :

British Isles

Europe

Amazon & Andes

North America

temperate Asia

Africa

Indian subcontinent

Malaysia & Borneo

Papua New Guinea

Australia & N.Z.

Moths of the World :

Britain & Europe

Amazon & Andes

South-east Asia

Caterpillars of the World

Insects of Amazonia

Butterfly Photography

Recommended Books

Species index

Subject index

Glossary

Links

Code of practice

Copyright - text & images

X

X

X

X

 

All photographs, artwork, text & website design are the property of Adrian Hoskins ( unless otherwise stated ) and are protected by Copyright. Photographs or text on this website must not be reproduced in part or in whole or published elsewhere without prior written consent of Adrian Hoskins / learnaboutbutterflies.com

Site hosted by Just Host