Holly blue - Celastrina argiolus

Family: Lycaenidae. Flight Time: March - October. Size: 26-34mm Altitude: 0-1900m

The Holly blue is a very widespread species, equally at home in city parks as in wilder habitats. It has a cyclical existence, every five years or so it dies out almost completely and then builds up to huge numbers by the end of the fourth year. I believe there is a parasitic wasp which preys on the larva which obviously has a similar cycle (just out of phase).