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Holly Blue
Celastrina argiolus
Distribution: North Africa and Europe except N UK and N Scandinavia.
Currently expanding northwards, in the UK at least.
Identification: Fairly distinctive with small blue points on an shiny
silvery blue underside ground colour. Resembles the Small and Short Tailed Blues
but the silver- blue underside is unique to C. argiolus. The silvery blue
undersides are noticeable distinct in flight. Its habit of flying around bushes
is also an aid to identification.
There is marked sexual dimorphism. The male has a fine black border on the
upperside, in the female this is very broad. Broadness in the female varies from
location to location and is generally greater in the summer broods. These broad
borders are clearly visible in flight.
Flight time: Flies in two or three broods. One of the first
butterflies to emerge in spring it can be found in April/early June, July/August
and then, in lower numbers, September/October. Amazingly I found a perfect male
on 20th January 2007 in Switzerland following exceptionally warm December and
January. I don't think he would have had much chance of finding a mate so far
out of season.
Habitat: Diverse but usually bushy or woodland areas. Often in
gardens. Larvae are polyphagous taking diverse plants, usually bushes. The
larvae eat the developing flowers or seeds. In the UK at least there is seasonal
preference for larval food plant - Holly being preferred in spring and Ivy in
the summer.
Behaviour: Unusually for the blues, it is typically seen flying around
shrubs, bushes and trees, rather than around grass and flowers. It rarely opens
its wings when at rest, being slightly more likely to do so in cooler
conditions.
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