Tuesday 21 August 2018

Holly Blues at Kingham 16th August 2018

Our driveway and the rear entrance to our house are surrounded by both a holly hedge on one side of the driveway and prolific ivy on a dry stone wall opposite our back door. Each year I keep an eye out for the delicate pale blue forms of Holly Blues which have been a presence ever since we first moved here over twenty five years ago.

Unlike other blues they are not colonial but are to be found in one's or two's fluttering about sheltered gardens and woods, and their behaviour is more akin to that of a hairstreak than any other species of blue butterfly as they can be surprisingly tame and allow close approach when they descend from their preferred high perches, almost to ground level, to feed or bask in the sun, as a female did today.

We do not see them that often, certainly not every day but we keep an eye out for them and occasionally notice them flitting about the holly and ivy and it is good to know they are about. They are great wanderers so it may be that the individuals we see have come from elsewhere but we like to think they are resident in our holly and ivy and are safe from insecticide and injudicious pruning.

The undersides of their wings are the palest blue, populated by just a few random black dots unlike the other blue species which exhibit a greater density of larger spotting, both black and orange.They do not fly strongly like other blues but flutter diffidently about the shiny green leaves of the ivy or hard spiked holly leaves in gardens and churchyards or anywhere else that is suitable, not only in villages such as the one we live in but also in many cities of England.

Refreshingly for our beleaguered native butterfly species they are increasing their range and now reach almost to the Scottish border but their abundance can vary hugely from year to year.This year seems to be a good one or at least it is where we live. The cyclical nature of their populations from year to year is due to two species of parasitic wasp that attack the caterpillars.

There are two broods of Holly Blues each year, the first flying from late March or early April to June and the second from late July to the end of August.

Today, in sunshine following the rain, a female flew from leaf to leaf of the ivy, fidgeting and never settling for long, but partially opening her wings to embrace the sunshine.The uppersides of the female's upperwings are bordered with  large, smudgy, dark margins giving the wings an ink blue pallor and shows strongest in individuals from the second brood. The male's wings, in contrast are pure blue.

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