During the 19th century the Speckled Wood suffered quite a contraction in its range, but since the 1920's it ha made a recovery. This has continued since the 1980s and may be due to climate change allowing it to spread further north (1).
1: Lewington, R. (2003). Pocket Guide to the butterflies of Great Britain and Ireland. British Wildlife Publishing, United Kingdom.
The trend for the Speckled Wood shows a highly significant and generally steady increase, as can be seen from the graph below produced by the UK butterfly Monitoring Scheme (3). The butterfly has a divided distribution in Britain (it occurs throughout Ireland) and it has continued to colonise new areas in both parts of its range during the monitoring period (3).
It has a flight season from April through to October, and is often found in woodland, but also anywhere that includes scrubland as well.
The larval food plants include False Brome (Brachypodium sylvaticum); Cock's-foot (Dactylis glomerata); Yorkshire-fog (Holcus lanatus); Common Couch (Elytrigia repens) (4).
Like any butterfly, male Speckled Woods can be pretty aggressive when defending their territory. These sparring sessions can last for up to 80 seconds (5), which must surely take a toll on the individuals.
3: UK Butterfly Monitoruping Scheme. http://www.ukbms.org/SpeciesFactsheets.aspx?speciesId=93
5: Wickman, P. and Wiklund, C. (1983) Territorial defence and its seasonal decline in the speckled wood butterfly (Pararge aegeria). Animal Behaviour. 31(4): 1206-16. http://www.sciencedirect.com/science/article/pii/S000334728380027X?via%3Dihub