A butterfly haven in an old limestone quarry

This is Ashes quarry, a former limestone quarry near Stanhope in Weardale that is now a wonderful nature reserve. The quarry floor is partially flooded and is a breeding place for dragonflies and damselflies, but this sheltered western end, which is mostly rough grassland and quarry spoil heaps, is always a good spot to look for butterflies.

It was good to see a small colony of wall browns has become established here. This is a butterfly that needs warmth and shelter, so this sun-trap, with its sun-warmed rock, clearly suits it very well.

Wall browns are very skittish insects, never settling for long in one place. This individual alternated between basking on its pile of rocks and feeding on herb robert flowers blooming amongst the stones.

The convenient supply of floral nectar meant that this one was constantly disturbed by rival males that tried to take over its domain. Wall browns are ferociously territorial, so each one of these incursions resulted in an aerial dogfight, as the butterflies spiralled upwards, so close to me that I could hear their wings clashing, before they separated and fluttered back to their respective territories.

Eventually a female arrived and courtsship began, with the pair walking through the grass and the male tapping the female with his antennae. I think the male is the closer of the two in this picture, with some wing edge damage that might have occurred during one of those bruising dogfights with a rival.

Wall brown colonies tend to be small and don't often persist in the same place for long, but this quarry site is sheltered and warm, with plenty of the caterpillar food plants (grasses), so it might last for a few years.

The warm piles of stones in the quarry are also excellent habitat for sun-basking common darter dragonflies ....

..... chirruping field grasshoppers Chorthippus brunneus

..... and this devil's coach-horse Ocypus olens. This beetle (more pics here) isn't often seen out and about in bright sunlight - it's more often seen in twilight.

Wall butterflies

It hasn't been a good year for butterflies here in North East England, so it was a delight to see several of these wall butterflies along the bank of the river Tyne downstream from Corbridge on Saturday ......

... either feeding on creeping thistle flowers or .....

... sunning themselves on the damp, sandy soil beside the river. The beautifully mottled underwing pattern, with the rows of 'eye' markings,  makes them quite difficult to spot against the sandy background, especially when they align themselves with the sun's rays so that they cast very little shadow .. but .....

 ... when they open those wings their pattern is very striking.

 It's remarkable how aggressive these butterflies are, with males defending their territories against all-comers with ferocious aerial dogfights, chasing each other in tight circles, even sometimes clashing wings.

The wall seems to be one of the species that is much less common in our region than it was thirty years ago, but this seems to be a very healthy population.

Wall Butterfly Behaviour

I’ve been watching wall butterflies lately, and their behaviour is fascinating. Have you noticed how, when they land, they fold their wings and shuffle around until their vertical wings are exactly parallel with the sun's rays – like the butterfly in the bottom photograph? I used to think this was some kind of defensive behaviour, so that their well camouflaged wings and body cast the smallest possible shadow. It's certainly easy to lose sight of them when they do this and if you look away they're hard to spot with their wings folded. But now I'm not so sure - I think the reason for this might be more subtle. When they orientate themselves like this it means that when they open their wings (see middle photograph) to bask their wings are at right angles to the incoming sunshine and so are perfectly positioned for absorbing the maximum amount of solar radiation. Maybe this is dual purpose behaviour and there's a grain of truth in both theories. I imagine the butterfly can tell, after it first lands, when its wings are aligned perfectly parallel to the sun’s rays because then neither eye would be shaded by the wings. They do seem to be very aggressive butterflies. The males that I’ve been watching patrol a well-worn footpath beside a hedge, engaging in brief aerial dogfights with rival males before seeing them off the premises. Courtship is an elaborate affair too. When a female arrives on the scene she indulges in a lot of wing vibrating, which I guess might be to drive off the volatile come-hither chemicals called pheromones that butterflies are known to use to attract a mate. The male flies around her and lands facing her, both insects with their wings outstretched, and them he seems to head-butt her and contact between their antennae takes place. Then I accidentally scared them both off (top photograph), so I don’t know what happened next................(the male is the settled butterfly on the right, with the broader diagonal dark brown stripe on the forewings)