As we steadily edge into Autumn, the main butterfly you are likely to see on Whiteknights Campus is the Speckled Wood (Pararge aegeria). Its third peak of emergence is approximately now, around the last week of August and the first two weeks of September. The appearance of this species is much like that of the Meadow Brown (Maniola jurtina) and Ringlet (Aphantopus hyperantus), as discussed in a previous blog however, on resting you will see that this species is not dull at all. You are most likely to see this species inhabiting the damp, shady sides of scrub/ woodland, darting around at low levels in the dappled shaded, from my personal experience. This is backed up by Davies, 1978, who found that territories involve the control of sunspots by males and as Davies found, males are most likely to be seen, as a result of this territory defense. The wing colouration in both males and females, consists of cream-pale yellow spots and eye spots, against a dark brown background, see image 1. Males and females are said to be told apart by the size of these spots, however, on research, I have found that there is great size variation in both and that actually, the females tends to have less of the cream – pale yellow spots overall. The underside of these wings mirrors the upper side, but the background is a paler brown. The wingspan is approximately 45-50mm.
Speckled Wood (Pararge aegeria) Female showing upper side of wings © Justin Groves The University of Reading
The Butterfly has a long flight season, with several overlapping generations these are :
- The adults are first seen in late March peaking the first time in early May
- The second peak is in late July
- The third peak being now, Late August – early September, with the last adults being seen in early October.
Interestingly, the long flight period is aided by their life-cycle. The species can over winter both as a larva and a pupa (the only UK species to do this), resulting in the early May peak (pupa from the previous year) and July peak (the larva from the previous year), the third peak (mainly in the southern England), is a result of the offspring produced from the May peak. This is because in optimum conditions eggs take 1-3 weeks to hatch, larvae – pupa takes around 25 days and pupa to adult can be as little as 10 days. Otherwise the larva and pupa can wait until the following year, as with the generation produced in July. Adults typically feed on honeydew (aphid anal secretions), on the trees and shrubs nearby although, flowers will be used in time of aphid scarcity, to obtain sugars.
The species is found throughout the UK, and after a contraction in range in the late 19th to the early 20th century, the butterfly is re-colonising, and spreading fully throughout the UK. The only area you are unlikely to see this species; is the border of Scotland and England and South, and South East Scotland. As with the other European species, it is also colonising further north across Europe. This is no doubt a result of temperature increases, the food plants it prefers these being; Cocks foot (Dactylis glomerata), False Brome (Brachypodium sylvaticum), Yorkshire Fog (Holcus lanatus) and Common Couch (Elytrigia repens) found throughout Europe and suitable habitats being found further north. The eggs are laid conspicuously on the undersides of leaf blades, with the larvae feeding from the edges to the middle of the grass blade, moving between plants for the best resources as it grows. The larvae are green in colour, feeding both day and night and will hibernate in the base of the plants over winter, with the larva going through 3-4 moults before pupation.
For more information you may wish to take a look at the links /papers below.
References:
Davies, N.B., 1978. Territorial Defence in the Speckled Wood Butterfly (Parage Aegeria): The Resident Always Wins. Animal Behaviour, 26, pp. 138-147
UK Butterflies, 2012. Speckled Wood. [Online] Available at: http://www.ukbutterflies.co.uk/species.php?vernacular_name=Speckled%20Wood
Butterfly Conservation, no date. Speckled Wood. [Online] Available at: http://www.butterfly-conservation.org/Butterfly/32/Butterfly.html?ButterflyId=56
The RSPB, 2012. Speckled Wood Butterfly. [Online] Available at: http://www.rspb.org.uk/wildlife/wildlifegarden/atoz/s/speckledwoodbutterfly.aspx
