Northern brown argus  (Aricia artaxerxes)

Hibernate: Hibernation is a winter survival strategy characteristic of some mammals in which an animal's metabolic rate slows down and a state of deep sleep is attained. Whilst hibernating, animals survive on stored reserves of fat that they have accumulated in summer. In insects, the correct term for hibernation is ‘diapause', a temporary pause in development and growth. Any stage of the lifecycle (eggs, larvae, pupae or adults) may enter diapause, which is typically associated with winter.
Single-brooded: Also known as ‘univoltine'. Referring to an organism which has just one brood each year.
Subspecies: A population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.

1. Still, J. (1996) Collins Wild Guide: Butterflies and moths of Britain and Europe. HarperCollins Publishers, London.
   
2. Carter, D.J. and Hargreaves, B. (1986) A Field Guide to Caterpillars of Butterflies and Moths in Britain and Europe. Collins, London.
   
3. Asher, J., Warren, M., Fox, R., Harding, P., Jeffcoate, G. and Jeffcoate, S. (2001) The Millennium Atlas of Butterflies in Britain and Ireland. Oxford University Press, Oxford.
   
4. UKBAP (March, 2002)
   http://www.ukbap.org.uk/ukplans.aspx?ID=109
   
5. Ravenscroft, N.O.M. and and Warren, M.S. (1996) Species Action Plan: Northern Brown Argus, Aricia artaxerxes. Butterfly Conservation, Wareham. Available at:
   http://www.butterfly-conservation.org/uploads/nba_action_plan.pdf