Holly Blue

(Celastrina argiolus)

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When seen in flight the Holly Blue can easily be confused with the Common Blue, but once landed the distinctive underwing pattern of small black dots on a uniform pale blue-grey background makes identification easy. Unfortunately, the underwing is all you usually see as they rarely open their wings when at rest. A male in flight can often be recognised by its rather "bluer" colour though, as it lacks the dark wing-tips of a female

First-brood males. Note the dark lines extending to the fore-wing margins which distinguishes the Holly Blue from the Common Blue - much more noticeable in the second and third images

First-brood females, flying from about April to June. As with the male, note the dark lines extending to the wing margins, which Common Blues do not have
The second-brood female has a slightly more purple colouring with darker, more extensive, markings which emphasise the black spots on the rear of the hind-wing	A view of both upper and lower wings shows all the typical characteristics of a (second-brood female) Holly Blue at the same time
Mating pair (first-brood). The female is on the right: note the dark margin to the slightly open wings	A better view of the mating pair: the female is again on the right (compare the up then down curved markings at the top of the male's wing)

Second-brood female (i.e. not the one from the pair above) egg-laying on an ivy flower-bud. First-brood females lay on holly (hence the name), second-brood on ivy: this change in larval food-plant is unique among British butterflies	A single disc-shaped egg, only 1mm in diameter, in position on an ivy bud. It should have hatched in about one week, but in fact did not - presumably because it was infertile	A freshly-deposited egg on the stem of a holly flower (yes, that barely visible dot just caught by the sunlight!). The first-brood female was seen to ovi-posit in this position not long before