A 7cm southern hawker dragonfly is observing me intently, using its 30,000 lenses to focus on my actions. As I venture further into the pond to remove strands of blanket weed, hoping to eradicate it with barley straw (which, by the way, isn’t very effective), the stunning green, black, and blue dragonfly darts towards me.
Now, I’m not one to back down easily. I’ve faced off against tough Fleet Street editors, endured the scrutiny of Royal Horticultural Society judges, and even hung from a rope out of a Royal Navy helicopter. But there’s something unnerving about the close attention that this southern hawker is giving me.
“I see that you’re protecting your territory so your mate can lay her eggs. Can you please give me some space?” I plead with the dragonfly.
To my surprise, the creature lunges at my face. “Your attitude towards garden insects is appalling,” it seems to say. Of course, it’s possible that my guilt-ridden conscience is playing tricks on me. “You need predators like us.”
In the interest of environmental conservation, I’ve invested in expensive biological controls to combat pests like red spider mites, chafer grubs, and slugs. Chemical control is rarely used in my garden, which means I face criticism and ridicule for letting weeds flourish. But I tolerate it all so that insects like the southern hawker can thrive and play their important role in the ecosystem.
However, I’ve also pulled out nettles, which serve as food for valuable pollinators like red admiral, small tortoise-shell, painted lady, and comma butterflies. Throughout the year, I’ve had to squash lily beetles, aphids, vine weevils, and countless other garden pests that persist through our mild autumns and winters.
And the southern hawker is right. The days when harsh winters could eliminate most garden insect pests in the UK are long gone. Nowadays, we rely more and more on alternative controls, such as predator insects.
At RHS Wisley, a rose garden in Surrey where chemical pest control is discouraged, dragonflies, along with lacewings and ladybirds, are hailed as excellent pest predators. Andrew Salisbury, head of plant health at the Royal Horticultural Society, explains that these beneficial insects play a crucial role in controlling pests like the lily beetle, which has plagued the garden’s lilies since the 1940s.
The battle against pests is not for the faint-hearted. Lily beetle larvae, for example, protect themselves by covering their bodies in feces to deter predators. Luckily, three species of tiny parasitic wasps have come to the rescue: Tetrastichus setifer, Lemophagus errabundus, and Diaparsis jucunda. Unfazed by the larvae’s dirty defenses, these wasps lay their eggs inside the pests, effectively eliminating them. These predatory wasps are now widespread in New England and are becoming more active in the UK.
Chemical control options do exist but are often ineffective. After battling the lily beetle for over two decades, I’ve learned that leaving the dirty work to birds, frogs, beetles, and tiny wasps produces better results. Adopting a chemical-free approach may sound effortless, but it actually requires a lot of back-breaking work, such as hand weeding. While I spend less time mowing, which creates more food and shelter for pest predators, I can’t resist digging out unwanted plants like hogweed, dock, nettle, and brambles in the visible areas of my lawn, for purely aesthetic reasons.
Fortunately, I’m not deviating from the RHS’s advice on pesticides. Salisbury affirms that the RHS recommends avoiding pesticide controls. Instead, they advocate for tolerating some damage, growing robust plants, and encouraging natural predators. Only when necessary should gardeners consider using biological controls.
Insecticides, with a global market value of nearly $84.5 billion in 2019 according to the Heinrich Böll Foundation’s 2022 Green Atlas, are just one of many threats that insects face. The State of Nature Report 2019, which involved over 50 organizations focused on recording, researching, and conserving nature in the UK, highlights the decline in abundance and distribution of UK species since 1970. The report expresses concerns about pollinators and other beneficial insects, largely due to the use of pesticides such as neonicotinoids. A report in Science from April 2020 supports these worrying trends, revealing a consistent decline of about 9% per decade in terrestrial insect abundance from 1925 to 2018.
Insects like earwigs, which feed on codling moth and prevent infestations in apples, pears, and walnuts, are under threat. Orchard owners have reported a significant decline in earwig numbers since the early 2000s.
According to research from the UK government’s Insect Decline and UK Food Security Committee 2023, flying insects in the UK have declined by 60% in the past 20 years.
Knowing your enemy is crucial in defending your garden. For example, badgers, crows, jays, and foxes can prey on chafer grubs and leatherjackets, which damage the grass roots. Vine weevils can be removed by picking out the maggot-like grubs from pot plant roots and leaving the remains overnight for birds to do their part. Aphids can be squashed or removed using a powerful jet of water, while ladybirds, lacewings, and dragonflies love to feast on them. Scraping scale insects off leaves or relying on ladybirds, lacewings, and parasitic wasps also serves as effective control. Red spider mites, which tend to hide on the underside of leaves, can be controlled by encouraging lacewings and minute pirate bugs with nectar-rich flowers and maintaining high humidity levels.
Without chemical control, what other options are there to defend our gardens? Rothamsted Research offers an early warning system for aphids through their weekly forecasts, available to both farmers and gardeners. These forecasts provide advanced notice of an impending aphid population surge, giving gardeners time to purchase and apply biological controls or dedicate more time to manual pest removal. RHS members also have access to a free gardening advice service for additional support.
Harnessing the power of insects to combat pests may seem contradictory, but it has numerous advantages. Insect-based control methods leave no harmful residues or negative side effects. Respected institutions like the RHS, RSPB, and the Natural History Museum all advocate for the use of insects and other biological controls as the best long-term solutions. This means creating insect-friendly gardens through practices such as low mowing, planting nectar-rich flowers, and providing bug hotels for beneficial insects to overwinter.
These principles are championed by Pestival, a short-lived celebration of music, art, and science that garnered support from insect specialists, comedians like Stewart Lee, and musicians like Graham Coxon and Robyn Hitchcock. Founder Bridget Nicholls, who spent three years at the London Zoo, shares the inspiration behind Pestival: her recovery from a severe illness while living near the London Wetland Centre in Barnes.
The declining insect populations and the mounting evidence of their importance necessitate a shift in our approach to gardening. By embracing natural control methods and creating habitats that support beneficial insects, we can contribute to the conservation of these vital creatures and the overall health of our planet.
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