Don’t dismiss the flies

Hoverfly Chrysotoxum sp on kniphofia, 8 September 2020.

With the possibility of down-sizing I need to get rid of some books, but it’s not easy. I can spend an afternoon considering two books before putting them back on the shelves. I was looking through some bound copies of The Gardener, a ‘Weekly Journal’ for 1901 when I came across an article on pollination in salvias. It reminded me of school lessons about sweet pea pollination.

This sent me looking through my photographs to see if I could see any of these flower parts that facilitate the process. In effect the flowers have evolved to accommodate the pollinators whilst ensuring cross pollination. The petals have formed a flower with two lobes. The stamens (initially five) have evolved into two that are effective; the first a fertile anther on a long curved connective of the filament that fits into the hood of the corolla, the second a short landing stage for the pollinator in the lower lip of the corolla. When an insect lands on the landing stage and forages for nectar, the curved connective is activated as a lever and it bends down to deposit pollen on the back of the insect.

The stigmas are also hidden in the hood of the flower and are activated by the pollinator, but only become fertile after the pollen has ripened and been dispersed, so that the pollen they pick up from the insect’s back is likely to have come from another flower. Brilliant.

The flower on the left (Salvia ‘Mellow Yellow’ I think) shows the large fertile anther and the stigma, 4 September 2020.

Thinking about pollination and pollinators I fear there has been a dearth of insects this year. On a sunny day last week the Buddleia x weyeriana ‘Sungold’ in the Upper Pool Garden was abuzz with bees and butterflies, but elsewhere in the garden was disappointing. Even the holes of the solitary mining bees in the Fountain Garden seem to have largely gone. There are plenty reports of rapid decline in biodiversity across the world, but usually the Walled Garden is uplifting in its fecundity. Not that there aren’t insects, but maybe just less this year. So I spent the morning actively looking for variety. I had fun back at home trying to identify some of the insects. I had not previously heard of sweat bees (said to be attracted to sweat) or nomad bees which are all cuckoos (parasites) of other bees. Without insects we would have few fruits or vegetables; there would be no food for the swallows, bats and badgers (and a host of others); the compost heaps wouldn’t rot, the seed packets we buy to glorify our gardens would be empty – but then we wouldn’t be here anyway.

Honey bee and tortoiseshell butterfly on Buddleia x weyeriana ‘Sungold’. Note the long tongue of the bee, 8 September 2020.
Bombus terrestris, the buff-tailed bumblebee, 8 September 2020.
Common carder bumblebee, Bombus pascourum, 8 September 2020.
Red admiral, 8 September 2020.
Peacock butterfly, 8 September 2020.

There are about 5,200 different species of true flies (diptera – two wings) in the UK all having a role to play in the ecosystem. Even the annoying midge has its role providing food for birds and bats (a bat can eat over 3,000 midges a day). The hoverflies are most obvious in the garden, mimicking bees and wasps. Not only are they important pollinators, many of their larvae eat aphids in quantity.

Hoverfly Eristalis tenax on Japanese anemone, 4 September 2020.
Hoverfly Syrphus ribesii on Osteospernum ‘Giles Gilbey’, 4 September 2020.
Possibly Halictus rubicundus – a type of sweat bee, 8 September 2020.
Though it looks like a wasp I think this is one of the nomad bees that parasitise other bees, 8 September 2020.
One of the bristle flies, probably Tachina fera, the larvae of which parasitise caterpillars, 29 August 2020.

I thought I should report back on some projects from earlier in the year. The mulching by Tim and Joanna under the staging of glasshouse 1 has paid off with the Abutilon ‘Kentish Belle’, A. ‘Canary Bird’ and Tibouchina urvilleana growing vigorously, the tibouchina will be a real show in a week or two, although, sadly, there is no access to the glasshouses at the moment. The croquet lawn is also looking good after all the tender loving care, and the grass paths of the White Border have had chance to recover. The Bukiniczia cabulica succulent that self-seeded in the cactus bed has thrived and another seedling has appeared nearby. The arbutus seedlings continue to thrive. The mulch, however, on the rose beds has not been the success that was hoped for and weeds are spreading rapidly. The Forsythia ‘Beatrix Farrand’ (28 March) has died. The wasps’ byke was attacked by something. A large hole appeared in the side and Andy was able to remove it. We puzzled about the culprit. Weasel? Pine marten? Whatever it was it solved a problem for Andy.

Abutilon ‘Canary Bird’ in glasshouse 1, 4 September 2020.
Abutilon ‘Kentish Belle’, 4 September 2020.
Abutilon ‘Nabob’ with carder bee, 4 September 2020.
Begonia luxurians has interesting fruits, 4 September 2020.
Bukiniczia cabullica, 4 September 2020.

Presently, priority for Mike and Steve has been hedge trimming. Steve has been mostly working in the nursery area and Mike has been using the MEWP. The MEWP broke down earlier and had to be replaced which delayed matters. Joanna has been taking cuttings of penstemon, salvias and other plants.

Mike finishes off the Egg and Eggcups, 8 September 2020.
Joanna takes cuttings of Penstemon ‘Vesuvius’, 8 September 2020.
Penstemon ‘Vesuvius’, 8 September 2020.
Gill and Judy tackle the June Border, 4 September 2020.
Sheila and Alison get instructions from Andy, 8 September 2020.

Now officially back as a volunteer garden guide, I am able to get to the inner parts of the garden and do my homework. In the Golden Garden I was taken by a yellow verbascum with mauve and orange centres to the flowers. Zooming in on my photograph I could see that the purple colour was due to hairy filaments and the orange to anthers – surely something to do with attracting pollinators. I could even see a hoverfly I hadn’t noticed visiting one of the flowers. I guess the plant is either Verbascum chaixii or V. nigrum. They are similar. The latter is the native plant, but rarely seen in Scotland. It’s a biennial that apparently seeds readily and is rabbit proof. In fact I could see some seeding amongst the nearby flagstones. I quite fancy it in my own garden. The white variety which grows beside it has the same purple and orange stamens. The more commonly seen great mullein, Verbascum thapsus, is also native and pops up here and there in the Walled Garden where it is usually welcome for its stately pose.

Verbascum sp showing the hairy filaments, the orange anthers and the single stigmas, 4 September 2020.
A white verbascum with marmalade hoverfly, Episyrphus balteatus, 8 September 2020.

Love-lies-bleeding, Amaranthus caudatus, has appeared in the garden this year. All the plants were grown from seed. The long tassels of flowers provoke different reactions: some dislike them, others find them stunning and others declare ‘interesting’. I reserve judgement but admit to ‘impressive’.

Aramanthus caudatus, 4 September 2020.

Hydrangea arborescens and H. paniculata are looking good just now. I think the large H. arborescens is ‘Annabelle’. It has such big flower heads that it is inclined to flop. ‘Annabelle’ is  not for a woman, but is named after the town of Anna in Illinois. Hydrangea arborescens is native to large areas of the USA. In contrast, H. paniculata is native to Japan, Korea, and eastern and southern China. I cannot always find names for the different cultivars, but Joanna found one H. paniculata ‘Kyushu’ on the South Border which I find was introduced by Collingwood (Cherry) Ingram from the town of Kyushu in Japan.

Joanna looks for labels on the lower White Border. Hydrangea paniculata ‘Kyushu’ is in the distance, 4 September 2020.
Hydrangea paniculata ‘Kyushu’, 4 September 2020.
In the foreground Hydrangea arborescens discolor ‘Sterilis’; in the background Hydrangea paniculata ‘Grandiflora’, 4 September 2020.
Hydrangea paniculata ‘Pink Diamond’ in the Rose Garden, 4 September 2020.

The nights are drawing in; the swallows and martins are gathering; the leaves are turning as is the year; and more Covid restrictions are in place. Take care everyone.

Postscript: I was just about ready to post this when I paused to watch Extinction presented by David Attenborough on the BBC. Referring to biodiversity someone remarked ‘its all joined up’. Enough said.

6 thoughts on “Don’t dismiss the flies

  1. Once again, thank you for a fascinating article Susan. Like you, I have noted a distinct lack of insects this year – I’ve even been missing the usual bothersome wasps, only a couple of hoverflies and no ants in the back garden – the first year ever. Watching David Attenborough was very depressing, but heartening to know so many people are taking positive steps… time will tell. Meantime, your latest article is a lovely informative, positive and cheering start to the week! Thank you!

    Liked by 1 person

  2. Hello – enjoyed the article. I’ve noticed the lack of insects – especially on the car windscreen and bumpers! Whilst the bee activity was slow to get going this year in my garden, they’ve been busier lately. I agree though, fewer wasps this year – or maybe I just got to the plums before them. There are definitely fewer ladybirds. Hoping that the lower level of grass verge maintenance will result in an increase of insects next year.

    Liked by 1 person

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