Introduction to the Speckled Wood Butterfly, Pararge aegeria
The Speckled Wood butterflies, eggs, caterpillars and chrysalis featured were recorded in South West England.
The Butterflies were mostly recorded between early Spring and late Autumn in a range of habitats including woodland, countryside hedgerows and gardens.
In much of the southern half of the British Isle the Speckled Wood is a common butterfly. Further north numbers decline although its range extends into some of the most northern parts of Scotland.
The Speckled Wood is also well distributed throughout much of Europe and into North Africa.
Speckled Wood butterflies have a wingspan of 47-50 mm.
Females are marginally larger, lighter and have more rounded wing tips.
In warmer parts of its range the ground colour is a pale orange.
Variations occur in the number and size of the yellowish spots.
Other Butterflies can be seen in The Butterfly Galleries and species pages
Speckled Wood Butterfly larval foodplants
The Speckled Wood caterpillars feed on a variety of grasses such as couch, annual meadow grass, false-broom and Yorkshire-fog
Those caterpillars featured below were either reared from eggs, swept at night or found during the day amongst grasses.
Chrysalis are those of reared caterpillars.
Speckled Wood Butterfly life cycle
In Cornwall the Speckled Wood butterfly may have as many as 4 broods between March and October and although it has been recorded in every month the earliest butterflies normally emerge between February and March
Uniquely for British Isles Butterflies the caterpillars of late broods may overwinter as either a caterpillar or chrysalis .
The Speckled Wood featured in the newspaper headline was an unusually early butterfly seen flying in our Cornish garden on the 13th of January.
Winters can be mild on the coast of South West Cornwall and mostly frost free. So presumably the chrysalis had been in a particularly sheltered spot and several days of sunshine triggered the butterflies premature emergence.
Speckled Wood butterfly egg
The egg featured above was seen being laid in our garden on a seemingly unappetizing scrap of Annual Meadow Grass (Poa annua) sprouting from an otherwise baron stone wall surrounding a little pond.
Many butterfly species appear quite meticulous in searching out healthy plants capable of supporting broods on which to lay.
However, on this occasion there seemed little chance of a hatching caterpillar surviving on such an unhealthy little plant.
Other Butterfly caterpillars can be seen in the Butterfly Caterpillar Galleries and species pages.
Moth caterpillars can be seen in the Moth Caterpillar Galleries and species pages.
Rearing the Speckled Wood butterfly
Having taken the egg inside to rear in an unheated room the caterpillar emerged within ten days.
The emerged caterpillar was 2 mm in length, yellowish-white, with a disproportionately large black head and pale hairs.
After the first moult it became light green with pale lines.
Noticeable changing features after the second moult were the pale green head, broad dark green dorsal stripe and whitish anal points.
Fully Grown Speckled Wood caterpillar
The Speckled Wood caterpillar was 28 mm in length and fully grown in 80 days. This long development time was likely to have been down to the cool conditions it was kept in. Earlier broods reared in warmer summer temperatures had been fully grown in 4-6 weeks.
Rearing was relatively easy.
Small rooted clumps of grasses were placed into a small plastic container containing a little water and dampened paper towel.
When the grass showed signs of browning a fresh clump was added and once the caterpillar had crossed on to it the old foodplant and frass was removed.
The caterpillar never moved far, feeding at night and was inactive during the day.
So lethargic was the caterpillar that it seemed unlikely it would have wandered off even if left with the container lid off.
Speckled Wood pupating caterpillar
Speckled Wood Butterfly chrysalis
From egg to chrysalis was 89 days. Due to the lower temperatures this was 2.5 times longer than late Spring and Summer broods reared.
Those Speckled Wood chrysalis not overwintering normally hatch after 3-4 weeks.
Should this caterpillar have not changed into a chrysalis to overwinter then it could have remained in this larval state for over 6 months.
The chrysalis was barely 10 mm in length – quite small for a butterfly and caterpillar of this size.
Those reared have mostly been green but they may also be dark brown.
Recommended Butterfly Books
Pocket Guide to the Butterflies of Great Britain and Ireland – Richard Lewington.
The Cornwall Butterfly Atlas – Watcher, Worth and Spalding
The Complete Guide to British butterflies – Margaret Brooks and Charles Knight.
Collins Butterfly Guide of Britain and Europe – Tolman and Lewington.
The Colour Identification Guide to Caterpillars of the British Isles – Jim Porter.