The Holly Blue is a small butterfly commonly found in gardens, and known for its bright blue hue.
   They are scattered across their habitat in 14 local sub-species. 
   They belong to the ‘Lycaenidae’ family, whose members all have varying shades of blue.
   Their wings are a bright blue.
   Females have black wing edges.
   Ventral sides are pale blue with small black spots which distinguish them from Common Blue.
   There are typically two broods per year, although this varies with some northern sites producing a single brood, and some southern sites managing to produce a third brood in good years.
    They mostly rest with wings closed or just partly open, revealing pale blue ventral wings with a few scattered black spots.

   When seen with wings open the male has pale blue wings edged with a fine black border and pale outer edge.

   The female has a broad dark border to the forewing and broken dark wedges around the back edge of the hindwing.

   It is difficult to catch these butterflies since, apart from being fast fliers, they prefer to fly above head height.

   These insects are the highest flying of the British blue butterflies.

   Holly blue populations fluctuate enormously from year to year as they are attacked by an ichneumon wasp which kills them in the larval stage.

   Subsequently, the decreased number of adults affects populations of the parasite, allowing time for the Holly Blue populations to recover and the cycle to start again.