Where are they found ? (in Britain and Ireland)
All Britain and Ireland, absent from the far north of England and southern and central Scotland and the Isles.
 
What is their preferred habitat outside gardens?
As its name suggests, the speckled wood likes to fly in partially shaded woodland but will also fly in parks and hedgerows if there is enough shade.
 
Resident or migrant?
Resident
 
When to see them?
The butterflies are usually around from early April until late September although small numbers are sometimes seen in March or October, especially in the south. Some males are territorial and perch in a sunlight spot waiting for females but others actively patrol in search of them.
 
What happens in winter?
Speckled woods are unique among British butterflies in that they can overwinter as caterpillars or as pupae. There are two or three overlapping broods during the year and whether the final brood caterpillars enter hibernation as caterpillars or reach pupation first appears to be dependent on the temperature when they are growing and moulting.
 
 
Speckled wood  Pararge aegeria   
Family: Nymphalidae   Subfamily: Satyrinae
Male
Female
Underside
(female)
What do they look like?
The upper wings have a dark brown background with several creamy-yellow spots (more on the forewings).  One of the spots on each forewing and, usually, three or four on each hindwing contain “eyespots” – black circles with a white dot in the middle and this is characteristic of the species. However there is often a slight regional variation in the markings.
 
Females tend to have larger creamy spots and appear a bit paler than the males.The underwings are paler, especially the hindwings, with a mottled appearance. Faint eyespots can sometimes be seen on the under hindwing and a more prominent one on the forewing.
 
The wingspan is between 46 and 52mm for males; 48 to 56mm for females.
What do the early stages look like?
Speckled wood eggs are a translucent light green, and laid singly on the underside of a leaf.  They hatch as small (2.5mm) green larvae and finish as bright green caterpillars – the main differences are that they are much bigger after the final (third) moult and the head has changed from black to green. Faint yellow and dark green stripes are noticeable when magnified.  The pupa is found attached to the base of a grass stem or in leaf litter.
 
What do the caterpillars eat?
The caterpillars eat grasses: mainly cock's-foot Dactylis glomerata, Poa species, and false brome Brachypodium sylvaticum although others are sometimes used. 1.
 
Flowers they take nectar from
The butterflies preferred source of calories is honeydew but when this is scarce, particularly early or late in the year, they will take nectar from flowers, such as brambles, common fleabane, cuckooflower, dandelions, ragworts and wild privet.2.
 
How are they doing?
Speckled woods are doing well and appear to be another species with a southerly distribution that has extended its range northwards since the 1970s in response to climate change. The 2022 State of UK butterflies report shows an increase in numbers of 108% since 1976 and an increase in range of 53% over a slightly longer period.3. The butterfly may also have benefitted from a reduction in coppicing leading to more shade. It is thought that the range could continue expanding but this will depend on having suitable woodland habitat.
 
Other interesting facts
A surprising number of studies have looked at mating behaviour in this species, where the females only mate once, but the males may mate many times.  Males may either patrol looking for females, or may take up a territory to defend in a sunny spot.  Females that go for successful territorial males are selecting for quality genes, but risk not being fertilised in their short life. Remarkably, males choosing the patrolling habit usually have three hindwing spots, while territorial males generally have four.4.
 
Butterfly enthusiasts holidaying in Spain or Italy may see a much brighter speckled wood as there are several subspecies and the predominant one in south west Europe has a paler brown background and orange spots.
 
References
 
1.   Biological Records Centre database
 
2.   UK Butterflies website
 
3.   State of UK Butterflies report 
 
4.   Useful sumary of mating behaviour here.
 
 
 
Page written by Judy Skinner, reviewed and compiled by Steve Head
Caterpillar
Pupa
Speckled wood  Pararge aegeria   
Family: Nymphalidae   Subfamily: Satyrinae
What do they look like?
The upper wings have a dark brown background with several creamy-yellow spots (more on the forewings).  One of the spots on each forewing and, usually, three or four on each hindwing contain “eyespots” – black circles with a white dot in the middle and this is characteristic of the species. However there is often a slight regional variation in the markings.
 
Females tend to have larger creamy spots and appear a bit paler than the males.The underwings are paler, especially the hindwings, with a mottled appearance. Faint eyespots can sometimes be seen on the under hindwing and a more prominent one on the forewing.
 
The wingspan is between 46 and 52mm for males; 48 to 56mm for females.
 
Where are they found ? (in Britain and Ireland)
All Britain and Ireland, absent from the far north of England and southern and central Scotland and the Isles.
 
What is their preferred habitat outside gardens?
As its name suggests, the speckled wood likes to fly in partially shaded woodland but will also fly in parks and hedgerows if there is enough shade.
 
Resident or migrant?
Resident
 
When to see them?
The butterflies are usually around from early April until late September although small numbers are sometimes seen in March or October, especially in the south. Some males are territorial and perch in a sunlight spot waiting for females but others actively patrol in search of them.
 
What happens in winter?
Speckled woods are unique among British butterflies in that they can overwinter as caterpillars or as pupae. There are two or three overlapping broods during the year and whether the final brood caterpillars enter hibernation as caterpillars or reach pupation first appears to be dependent on the temperature when they are growing and moulting.
Underside
(female)
Male
Female
Caterpillar
Pupa
What do the early stages look like?
Speckled wood eggs are a translucent light green, and laid singly on the underside of a leaf.  They hatch as small (2.5mm) green larvae and finish as bright green caterpillars – the main differences are that they are much bigger after the final (third) moult and the head has changed from black to green. Faint yellow and dark green stripes are noticeable when magnified.  The pupa is found attached to the base of a grass stem or in leaf litter.
 
What do the caterpillars eat?
The caterpillars eat grasses: mainly cock's-foot Dactylis glomerata, Poa species, and false brome Brachypodium sylvaticum although others are sometimes used. 1.
 
Flowers they take nectar from
The butterflies preferred source of calories is honeydew but when this is scarce, particularly early or late in the year, they will take nectar from flowers, such as brambles, common fleabane, cuckooflower, dandelions, ragworts and wild privet.2.
 
How are they doing?
Speckled woods are doing well and appear to be another species with a southerly distribution that has extended its range northwards since the 1970s in response to climate change. The 2022 State of UK butterflies report shows an increase in numbers of 108% since 1976 and an increase in range of 53% over a slightly longer period.3. The butterfly may also have benefitted from a reduction in coppicing leading to more shade. It is thought that the range could continue expanding but this will depend on having suitable woodland habitat.
 
Other interesting facts
A surprising number of studies have looked at mating behaviour in this species, where the females only mate once, but the males may mate many times.  Males may either patrol looking for females, or may take up a territory to defend in a sunny spot.  Females that go for successful territorial males are selecting for quality genes, but risk not being fertilised in their short life. Remarkably, males choosing the patrolling habit usually have three hindwing spots, while territorial males generally have four.4.
 
Butterfly enthusiasts holidaying in Spain or Italy may see a much brighter speckled wood as there are several subspecies and the predominant one in south west Europe has a paler brown background and orange spots.
 
References
 
1.   Biological Records Centre database
 
2.   UK Butterflies website
 
3.   State of UK Butterflies report 
 
4.   Useful sumary of mating behaviour here.
 
 
 
Page written by Judy Skinner, reviewed and compiled by Steve Head
       Garden Wildlife
             Garden Wildlife