The Year of the Red Admiral

I can't recall an early autumn when I've seen so many red admiral butterflies. It seems to be an exceptionally good year for them here in County Durham, both in our garden and in the wider countryside. 

A red admiral with its black and scarlet wings outstretched, basking in the afternoon sunshine, is a magnificent sight but the undersides of the the wings have their own distinctive beauty. When they are folded they provide a degree of camouflage, with their dark dead-leaf colours, but closer examination, with the aid of brighter light, reveals an exquisite, intricate pattern of scales in shades of brown, grey, blue and green.

The three plants that attract them most in our garden in September are ice plant Hylotelephium sp., ivy and Buddleia x weyeriana, but they also congregate in the company of comma butterflies on rotting fallen apples and pears, becoming sluggish and inebriated under the influence of fermenting juice. 

heather moorland in August

 The moorlands of Weardale are a sea of purple heather at the moment, often stretching all the way to the horizon. Billions of tiny, nectar-rich flowers are in bloom, feeding vast numbers of insects, from minute thrips to butterflies.

The flowering of the heather coincides with the breeding season of these heather Colletes bees (Colletes succinctus), below. They lay their eggs in tunnels excavated in the sandy moorland soil, usually on a south facing patch of bare ground, then provision the egg with heather pollen before sealing the chamber. They're solitary bees, unlike the highly organised, social nests of honeybees and bumblebees, but do aggregate their nests in huge colonies. Yesterday we must have walked past many thousands of them, congregating at the entrance to their tunnels and shuttling backwards and forwards to the heather flowers.

The vast expanse of flowers also attracts butterflies. Yesterday we saw red admirals, small coppers, small tortoiseshells and small heaths. The small coppers breed on dense, transient patches of sorrel that grows quickly on the bare soil after a heather burn.

This 'woolly bear' caterpillar (below) is the larva of the northern race of the oak eggar moth Lasiocampa quercus. It spends two years in the larval stage, overwintering as a larva before emerging to feed again, then pupating over a second winter before it finally emerges as a spectacular moth.

And finally, a rove beetle Platydracus stercorarius, with wings tightly folded under those red wing cases

Butterfly alcoholics

Thursday's Guardian Country Diary is all about intoxicated butterflies.

We had our best ever plum crop this year - too many to eat, store in various forms or give away all of them. Branches broke under their weight.

The beneficiaries from those that fell on the ground were red admiral butterflies. I piled some plums on the bird tables, where the natural yeast on their skins fermented the juice to produce an alcoholic liquor that stupified the butterflies that fed on it. The whole area under the tree smelled of vinegary alcohol after a few days in the sun.

Sometimes there were a dozen or more red amirals on the bird table, where they usually tolerated each other as long as their wings or antennae didn't touch. If they did they flicked there wings, clearly irritated.

If  other butterfly species tried to join them - and peacocks and speckled woods sometimes did - the red admirals became more aggressive and chased them away.

The red admirals were clearing drunk and had lost their inhibitions. If I put the fermented plum pulp on my fingers they extended their proboscis and drank from my skin.

And if I deliberately chased them off they just flew around my head, landing in my hair or on my clothes and hands.

Some days they were so drunk that I could poke them on the nose and they wouldn't take flight.

The last of the plums has now rotted and the red admirals have returned to their favourite nectar source in the garden - Buddleia x weyeriana, which flowers right up until the frost. But all the time the plums were available they completely ignored it, confirming my suspicion that they had fallen under the influence of the demon alcohol.

Berries

This must surely be the best year for hedgerow berry crops in recent memory. Last year there were very few berries available when the first of the winter flocks of redwings and fieldfares arrived, but this year the fieldfares that we saw pouring into Teesdale on Saturday were greeted with an almost inexhaustible supply. 

Hawthorn

Hawthorn

Rowan

Rose hips

Mild, wet weather has encouraged fungal growth, causing many of the rose hips to begin to rot, so their juices are attracting the last of the red admirals.

In praise of some non-natives

Wildlife gardening evangelists frequently exhort us to plant native species in our gardens - quite rightly, as there are indeed many native plants that are decorative and provide valuable resources for insects and their larvae. 

But when it gets to this point in autumn the choice of flowering natives is pretty narrow. There's ivy, which is certainly a terrific source of pollen and nectar for insects and also food plant for holly blue butterfly larvae, but that's about it  - other that a few late hogweed flowers and yarrow, which flower up until the first frosts but don't bring much colour to a garden.

So that's when Michaemas daisies Aster amellus, whose natural range extends across southern Europe into Asia, come into their own. Whenever the sun shines the Michlaelmas daisies in our garden attract a constant stream of visitors, including ....





.... hoverflies, like this Heliophilus pendulus

..........honeybees ......

.............. small tortoiseshells ............

.............and red admirals, all photographed in the space of a few minutes at the end of last week.

Marigold Calendula officinalis, which originated in southern Europe, provides similar services for butterflies throughout autumn.

Buddleia davidii, the famous butterfly bush from Central China and Japan, has - until recently - been a favourite amongst wildlife gardeners as a nectar source for butterflies, even though it usually finishes flowering long before the late autumn generation of small tortoiseshells, peacocks, red admirals and commas get into their stride. These days conservationists give B.davidii the thumbs down, on account of its invasive tendencies, but there is a much better Buddleia alternative - B x weyeriana, which is an interspecific hybrid between B.davidii and B.globosa and has very attractive pinkish-orange flowers and none of its parent's tendency to seed itself around prolifically. It's extremely hardy and continues to flower long after the first frosts, offering a 'last-chance saloon' for any insects that need to top up with nectar before going into hibernation.

Red Admiral hairy eyes

One of the pleasures of macrophotography is that you tend to notice things in the captured image that you'd never be aware of otherwise.

Until the colder weather arrived a couple of days ago we had several red admiral butterflies in the garden. I took some extreme close-ups of them, while they were feeding on ripe pears, and noticed in the images .....

.... that their eyes have this strange hexagonal pattern. Looking closer still, it's clear that .....

.... the eye surface is hairy and it looks like it's the pattern of hairs, located in between the individual ommatidia of their compound eyes, that is responsible for those large pale hexagons. A comparison with eyes of other common butterflies, like...

..... this small white, shows a pattern of darker patches on the eye but not a hint of hairiness around the ommatidia.

So I wonder what the hairs' function might be? Maybe they enhance flicker vision - the sensitivity of compound eyes to movement of objects across the field of vision............? 

Hairy eyes are not uncommon in insects - click here, for example, to see a scanning electron micrograph of a honeybee's hairy eye. Another possibility of that the hairy surface might stop pollen sticking to the eye surface in these flower-visiting insects.........

The irresistible attraction of fermented plums

After a bumper plum harvest, the last few fallers have attracted a host of insects, including ......

...... bluebottles and greenbottles ........

....... hosts of these little vinegar flies (aka fruit flies) .....

...... a yellow fly with red eyes that might be a dung fly .....

..... and several of these lovely red admirals.

The Best Buddleja for Butterflies?

The 'butterfly bush' Buddleja davidii, an import from China that has become firmly established in the wild in Britain, is famed for its ability to attract butterflies. Unfortunately its flowering time does seem to be shifting ever-earlier - as a result of climate change, according to some experts who I've talked to - and its certainly the case that there were very few butterflies on the wing when the plants in my garden were at the peak of flowering back in the summer. In contrast, this orange late-flowering hybrid, Buddleja x weyeriana (a hybrid between B. davidii and B. globosa) - has been feeding red admirals, commas and small tortoiseshells (not many of the latter around this year) since early September and will be providing bees and butterflies with nectar right up until the first frost. This shrub is the 'last chance saloon' for an energy  top-up in my garden: highly recommended.