insects – Charlton and Blackheath Amateur Horticultural Society

May 2024 Talk: Silent Earth – Averting the Insect Apocalypse

Dave Goulson, Professor of Biological Sciences at the University of Sussex specialising in the ecology and conservation of insects, and author of several books*, gave a talk about the dramatic insect decline worldwide. He outlined some of actions required on a National and International scale to reverse this apocalypse and what we as gardeners can do.

Dave Goulson with our Chair, Stella and the range of his books for sale at the meeting

When he was a boy, he started collecting caterpillars (in his lunchbox) and his interest in insects became a life long passion when one of them pupated into a Cinnabar Moth. He explained that insects evolved over 480 million years ago and there are now around one million known species worldwide. They were the first creatures to fly and sing and many have complex inventive ways to camouflage themselves or mimic others. Examples of some ‘weird and wonderful’ insects were shared with us such as the Shield Bug from Thailand whose back very much looks like the face of Elvis.

The horrifying statistics on insect decline were shown, particularly over the last 30 to 40 years. Studies show that the decline is around 75%. He has researched the Shrill Carder Bee which was common across Southern England pre-1960 but by the year 2000 the populations of this bee had greatly decreased and there were only about six populations left. Since 2000, the population which inhabited the Salisbury Levels has become extinct.

May 2022: Val Bourne on ‘Butterflies in Gardens’

CABAHS welcomed Val Bourne to speak at our May meeting, sharing her photographs, experience and knowledge of butterflies in the garden. She emphasised that she is not a butterfly expert (but she knows one!), she’s an organic gardener who has spent a lot of time observing butterflies, their habits and preferences – and, sadly, their decline in recent years.

Photograph of the FSC's Butterfly ID chart

As a starting point, Val recommended a book and a tool: ‘The Philips Guide to Butterflies’ and the Field Studies Council’s butterfly identification chart. Butterfly Conservation also provide a range of identification guides online. Photographs of a wide range of species – 24 different ones have been spotted in the Spring Cottage garden – showed us the beauty of even the smallest, brownest examples!

Val explained how useful even a small meadow area is for many species, how some species rely on quite a narrow range of plants for nectar, and how the timing of a butterfly lifecycle is intrinsically linked to the lifecycle of their food plants. She stated that climate change – causing plants to flower at different times – is demonstrably messing up this synchronisation, so as gardeners it’s important to grow a wide range of butterfly-friendly plants to try to mitigate that situation.

Some examples of butterfly-friendly plants, and the butterflies that particularly need or enjoy them:

Musing on poisonous practices

In his book The Flower Yard, Arthur Parkinson writes lovingly about his grandmother Min and her gardening practices, typical, he writes, of an older generation of gardeners. He describes the kinds of plots tended by Min and her neighbours and how ‘there was no acceptance of insect life, as proved by the cupboard of death in the garage, its shelves packed with poison, weed killers and bug spray’[1].

My Mother’s death bequeathed to me not only her gardening tools, but a similar shelf’s worth of gardening aids. I have very vivid memories of the shed she and my Father had in their garden, the tools neatly lined up and clean, sweet jars ready for pickled vegetables, saved seed in envelopes and plant labels ready to be re-used. But alongside all this were also the toxins.

And it is not only a younger generation of gardeners who believe in far more environmentally friendly gardening practices. In a recent online talk given by Fergus Garrett, he argued that ‘gardening and ecology have to come closer together’ and devoted one whole lecture to how gardening at Great Dixter has become much more sustainable in recent years and delighting in the huge quantity of species that the gardens are home to.

Driving somewhere in the 1970s meant cleaning the windscreen and headlights of bugs on arrival home. That no longer happens and is a sure indication of how much insect life has been destroyed in a very short space of time.

Vija

[1] Parkinson, A. The Flower Yard (2021) Kyle Books p.119.

Butterflies and sunflowers

Beautiful picture of Gatekeeper butterflies enjoying Sharon’s garden. Lysimachia clethroides is grown here with Anthemis “Cally Cream” near a Hydrangea Limelight in a pot.

These are Sunflowers, Helianthuis debilis “Vanilla Ice” growing daintily in Sharon’s garden, producing new flowers continually as she deadheads them.

In praise of… earwigs!

I have not been an earwig lover for all of my life. As a child, I remember my father making a nightly check on his prize dahlias and coming back into the kitchen with earwigs crawling out of the turn ups of his trousers. My mother’s predictable reaction meant that I thought earwigs were definitely not insects one was meant to love. Now years later, in my own garden, I can see the results that a small earwig population have on my own favourite Dahlias, Verrone’s Obsidian, and it’s extremely annoying. But this Christmas my husband gave me a book – “The Garden Jungle” by Dave Goulson and it has rather opened my eyes to the trials and tribulations of this little insect.

Goulson points out that earwigs are easily eradicated by sprays, and because they don’t fly and only produce one generation a year, they don’t re-colonise very quickly once they have gone. I haven’t used pesticide sprays for some years, with the exception of a drench for vine weevil in my containers, so I know I do have earwigs in the garden, although not in the numbers I remember as a child.

Earwigs are overwhelmingly beneficial insects, they feed voraciously on aphids, as well as munching on the occasional petal. In orchards where earwigs have been sprayed out of existence, trees are infested with three times as many woolly aphids as those with a good earwig population. It is generally the case that beneficial predators of a crop pest breed more slowly than the pests they feed on. Aphids, in particular, breed spectacularly fast, giving birth to live young which themselves have developing offspring inside them when they are born. In contrast, Mrs Earwig produces maybe 50 offspring a year, laying creamy eggs in a burrow in the ground towards the end of winter. She tenderly cares for the eggs, guarding, cleaning and turning them and looks after the young brood (nymphs) until they moult and gradually become independent. Then she turns them out of the burrow and they must look after themselves, foraging at night and hiding in the day in any crevice (or dahlia) they can find. They must do this all Summer and Autumn dodging predators while they grow, until winter comes and they find a mate and it all starts again.

The fierce looking pincers are actually quite feeble and incapable of doing harm to a human, they are used by the earwig in defence against predators such as ground beetles, and also in mating. The “wig” part of their name comes from an old word for “wiggle” and they definitely never burrow into ears!

We should certainly see earwigs as our friends in the garden, just as we now do ladybirds and lacewings. I have decided that a nibbled petal here and there is a small price to pay for all the good they do.

Kathy