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
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
3. State of UK Butterflies
report
4. Useful sumary of mating behaviour
here.
Page written by Judy Skinner, reviewed and compiled by Steve Head