The Chalkhill Blues

Some years ago an unknown person decided that they would introduce Chalkhill Blues (Lysandra coridon) to the Iron Age hill fort at Warham in north Norfolk.  The ‘authorities’ frown upon such activities, and yes putting an alien species into the wrong habitat can be disastrous, both for the habitat and the introduced species.  You only have to witness the effects that grey squirrels and mink have had!  However these butterflies have thrived, though their numbers fluctuate.  There is plenty of horseshoe vetch their only food plant and they do not compete with any other species, so for me all’s good.  The colony is however a long way from any other, the nearest being Newmarket 60 miles away.

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Backlit Chalkhill Blue

As the long hot summer continues I thought it about time I had a look for the Chalkhills.  I was amazed at how many there were, especially females.  Hundreds of milky blue males danced low over the banks of the ring ditches looking for newly emerged females.  Females that had already mated and were looking to lay eggs were having to fight off the unwanted amorous attention of sometimes up to four males.

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“What do you mean you don’t like me? What’s wrong with me?” A worn female rejects a very battered males advances

Perhaps it was too hot and sunny, it was very difficult to photograph a male with open wings in a nice setting, I’ve done better in previous years, check out the HOME page and tab ‘Iron Age Blues, Warham Camp’  When a little bit of cloud covered the sun the males did start to settle, but low down.

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A fairly fresh male Chalkhill Blue

It was nice to see so many butterflies of other species today including the years first Wall Brown (Lasiommata megera)  The numbers of these in this part of the Country is very low compared to when I was young.

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“Can’t see me” The superb camouflage of the Wall Brown

The Brown Argus

I really enjoy my visits to Warham Camp in the summer.  The two huge ring ditches that surround the 2,000 year old Iron Age fort are made of chalk.  This has created a rare habitat for Norfolk and many beautiful plants grow on the steep sides, these in turn support a healthy population of fascinating insects including the Brown Argus (Aricia agestis).

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Male Brown Argus keeping watch from atop a stinging nettle while my knees suffered!

Last week while watching the Common Blues I was keeping my eyes open for this small butterfly.  Due to size, colouration and the speed they move at they can be difficult to spot, however they are fiercely territorial and will launch themselves at any unsuspecting passing insect, and this is what gave away the presence of this fellow.  Unfortunately for me he had chosen a bed of stinging nettles to defend, and although he allowed me to approach to within a few inches, I swear you could hear him laugh as my knees got badly stung!

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Enjoying the sun

The Brown Argus is found in the southern half of the UK.  It has a wingspan of 25-31mm (1- 1 1/4 inches).  The caterpillars feed on common rock-rose or cranesbill.  The adults emerge in May and June with a second brood late July through to September.  They prefer sunny chalk downs but can also be found in coastal sites.

 

Common Blue

The weather has been a bit miserable the last few days.  Sunday promised a spell of sunshine, so we headed thirty miles west around the coast and visited one of my favorite butterfly sites, the Iron Age hill fort, Warham Camp.  It was a good decision, the sun shone and it was very warm with the lightest of breeze.  Perfect conditions for finding the Common Blue (Polyommatus icarus).

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Male Common Blue

The Common Blue is the UK’s most widespread member of the ‘Blue’ family, it can be found on most sunny grassland sites where the food plant of the caterpillar, bird’s-foot trefoil or lesser trefoil, occur.  It is a small butterfly with a wingspan of 29-36mm (1 1/4 – 1 1/2 inches).  Like some other Blues the females upper wing is mostly brown edged with an orange band, though some colonies have a lot of blue colouration.

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Common Blue under wing

The under wing, like most Blues, has a lot of eye spots.  The old English name was Blue Argus, Argus in Greek mythology was a god with a hundred eyes.  The blue colouration can vary, some are so vivid as to be almost violet.

Several Common Blues were seen including egg laying females, this is the first brood, there is a second emergence in late July.

And as we drove home the fog once more rolled in off the North Sea.