The insect apocalypse is negatively affecting the world in ways that we are only beginning to understand, and if we continue on our current path, insect decline and the loss of biodiversity across all types of animals and plants will not only continue, but also accelerate. To help us understand the scope of the problem and explain ways we as gardeners can help reverse this trend, Professor Dave Goulson joins me on the podcast this week.
Dave is a professor of biology at the University of Sussex in England. He specializes in bee ecology and founded the Bumblebee Conservation Trust. He’s published more than 300 scientific articles on the ecology and conservation of bumblebees and other insects and has received numerous awards for his work from research and conservation societies. He’s also the author of eight books, most recently, “Silent Earth: Averting the Insect Apocalypse,” “Gardening for Bumblebees: A Practical Guide to Creating a Paradise for Pollinators” and “The Garden Jungle or Gardening to Save the Planet.” In his writing and appearances, he motivates gardeners and others to recognize and care about the threat of insect decline and shares how to encourage wildlife in gardens.
Dave lives in East Sussex in South East England, where he gardens on 2 acres, half of which is orchard with heritage apple varieties, plums, cherries, medlers, quinces and more. A fruit cage and vegetable beds are fenced off to keep rabbits out, but his property has lots of wildlife-friendly areas.
“It’s not the neatest garden you’ve ever seen, but it’s full of life,” he says. “It’s full of flowers — lots, lots of wildflowers.”
He adds that he doesn’t worry too much about weeds and that, in fact, many weeds are fantastic resources for pollinators and may be beautiful native wildflowers.
Dave’s garden is also organic: “I wouldn’t dream of using any pesticides in my back garden. I just think it’s madness. Why would you spray poison where your kids play and where you grow food to eat?”
This topic is right down the strike zone for me, and I know the same is true of regular listeners of the podcast. If you have been a listener for some time, you know the importance of insects in our gardens and in the world at large, and you know why you should plant more natives and refrain from using pesticides. Dave helps drive home these points and encourages us to be messengers who will spread the word to others.
Before proceeding any further with this week’s topic, I want to take a moment to remind you that I have a new book coming out in September, and it’s available for pre-order now. The title is “The Vegetable Gardening Book: Your complete guide to growing an edible organic garden from seed to harvest,” and I’m very excited for you to read it. It’s chock full of insider tips and new-to-you information that will help you step up your gardening game and tackle challenges.
How Dave Goulson Came to Love Insects
Dave’s entree into the world of insects began with collecting caterpillars and researching what types of leaves to feed them. He said he was fascinated with bugs from a very young age like most people are, but while others grew out of it, he never did.
From the age of 5 or 6, Dave would find caterpillars, stick them in his lunchbox and take them home. Once he got them home, he tried to keep them alive. He admits that he probably killed more than he managed to nurture, but when he was successful, the caterpillars turned into moths and butterflies. To him, it felt like magic, and he was fortunate enough to turn his childhood passion into a career.
‘The Garden Jungle’
In 2019, Dave published “The Garden Jungle,” about the life that lives in a backyard.
“It’s kind of slightly about my own garden, of course, and the various other gardens I’ve had over the years,” he says. “It’s just amazing how many different types of creatures there are right under our noses, under our feet, if you take the time to look, which of course most people rarely do.”
People look at colorful birds, he says, but they rarely look at worms, beetles and aphids. “They’re amazing, and they have really weird lives and life cycles and behaviors, and some of them are stunningly beautiful and most of it is just really unappreciated.”
Dave’s most recent book, published in 2021, is “Silent Earth: Averting the Insect Apocalypse.” He admits that it is a harder-hitting book than his earlier ones.
A lot of the content is shocking, depressing and not easy-reading, Dave says, but he adds that he tried to lighten things up by celebrating how amazing insects are and sharing vignettes about certain weird insects.
“The final quarter of the book is all basically about what we can do, how we can fix these problems, how we can all get involved,” he says. “And that’s the important bit really: That there is a crisis, but it isn’t too late. And trying to inspire people to do something themselves, to turn this around. Because if enough people do it, it will work.”
It’s so true. The world’s population seems to be ambivalent about these things, and we need to wake them up to the importance of it by talking about why insects matter.
Why Insects Matter
Love them or loathe them, insects are incredibly important, Dave says. They make up the bulk of life on Earth, more than two-thirds of all known animal and plant species, he points out.
That means that, so far, we’ve named about 1.5 million animal and plant species, and more than 1 million of them are the insects. And Dave says there are probably another 3 million to 5 million undiscovered insect species on the planet, with new ones being described every day.
Dave notes that insects are involved in every ecological process you can think of: they recycle all sorts of organic matter (dead leaves, tree trunks, even dead bodies) which is important to nutrient cycling, plant growth and crop production. They also provide biocontrol and keep the soil healthy. There are umpteen other things insects do, but the one “ecosystem service” that is the most well known and appreciated is pollination. Nearly 90% of plant species and three-quarters of the crops we grow need pollination by some sort of animal, and that animal is almost always an insect.
“We have a really direct connection to these little creatures, which is why we need to look after them,” Dave says. “And I think the pollination story is a really good place to start if you want to convince people that they really need to pay attention here — there’s an issue that affects them. Even if you live in a city, you never go to the countryside, your food turns up in the shops thanks to bees and other insects, and we need to make people realize that.”
The Insect Apocalypse
Some insect species may go extinct before we ever learn of their existence.
In “Silent Earth,” Dave cites an entomological study conducted from 1990 to 2015 in Germany, measuring the biomass of insects. It was alarming what they found out.
“The headline figure is terrifying,” Dave says. The researchers discovered that in a quarter of a century, 76% of the insect biomass disappeared across Germany.
There is evidence that the decline is happening in places far beyond Germany. Anecdotally, Dave recalls how when he was younger the car windshield would become covered in insects while driving in the summer, and now that’s no longer the case. I’ve noticed the same thing, though Dave says many people don’t think about this change because it happened gradually over their lifetime.
Dave raises some concerning statistics: Monarch butterflies are down 80% in population in just 20 or so years in the United States, and butterfly populations in the United Kingdom are down about 50% in 40 years.
The Causes of Insect Decline
Habitat loss has been the cause of a great deal of insect decline and it continues to be a big contributor. Particularly in developing countries, where rainforests are being burned down, habitat loss is happening rapidly. And much of that land is being turned over for agricultural use, where crops are grown in monocultures with heavy pesticide use.
Light pollution can mess up the navigation of night-flying insects and the timing of their life cycles as they misjudge day length. They used to navigate by the light of the moon, but now there are lights in all directions.
Climate change is only just really beginning to impact insects. “There’s a little bit of evidence that some of them are shifting their ranges or disappearing at the warmer parts of their ranges as the temperature increases,” Dave says.
Even fertilizers contribute to the death by a thousand cuts that insect populations are experiencing. This one is less obvious than the others, Dave acknowledges. While it’s clear why pesticides are bad for insects, the problem with fertilizers takes some explaining. “It has quite profound effects on ecosystems,” he says. The reason is that when nitrogen fertilizers are applied to a landscape, grasses grow twice as fast, outcompeting all the wildflowers that insects rely on. “You very quickly end up with a flowerless bright green pasture instead of a beautiful flower-rich pasture,” he says.
Plants grown in high nitrogen conditions may also be less palatable to herbivorous insects. “There’s a whole kind of raft of quite subtle ecological effects that we’re only just really beginning to appreciate,” he says.
Fertilizers also leach into streams, ponds and bays, causing algal blooms that are harmful to marine life and can even be toxic to humans and pets.
Pesticides, the Obvious, Ubiquitous Culprit
Pesticides have a significant impact on insect populations. Many insecticides, whether chemical or organic, are indiscriminate, meaning they kill neutral and beneficial insects they come in contact with as well as true pests of food crops and ornamentals.
Even plants that are marketed as “bee-friendly” may be treated with a cocktail of pesticides. Dave says a test on a Heather plant found 10 different pesticides — and it was being sold as bee-friendly.
“There are lots of very lovely people trying to attract pollinators to their gardens,” he says. “They want to grow the right kinds of plants. They pop to the garden center, they see all these lovely plants with the labels on them saying, ‘bee-friendly.’ And they, with the very best of interests, they’re buying those plants and they’re accidentally poisoning the bees in their garden.”
One troublesome class of pesticide is neonicotinoids. Chemically related to nicotine, neonicotinoids affect insects’ nervous systems. Neonicotinoids are taken up by plants’ roots and transferred to the leaves, flowers, pollen and nectar. That pollen and nectar becomes toxic to bees.
Dave says some insecticides are even labeled as “bee-friendly,” and that drives him mad.
For gardeners, there is no need to use pesticides, according to Dave. “We can all manage without pesticides,” he says. “I’ve done it for donkey’s years now, and I really don’t think there is any justification.”
A few aphids on your beans can be left alone — an army of little creatures will show up and eat the aphids for you, Dave says. Worst case scenario, you may end up with a tinier harvest. If you did spray your way to a greater harvest, do you really want to eat those beans that were covered in pesticides?
“It may be more labor intensive, but you can produce a heck of a lot of food off a small amount of land without any chemicals at all if you just encourage a healthy ecosystem,” Dave says.
How to Connect an Audience to the Vital Role Insects Play
Motivating people to care about insects and change their behaviors is exceedingly difficult. At least 90% of the population aren’t worried at all about insect decline and biodiversity loss isn’t on their radar, Dave says. That’s not because they are bad people, but because they have other worries, like raising a family and paying the bills.
“Our children and our grandchildren are going to have a much harder life if we don’t look after the planet because they will be inheriting an impoverished world with the soils all depleted, a lot of the natural beauty wiped out, all those beneficial insects gone, and life will be really tough for them. And if people knew that, if people understood that their kids will be worse off because we’re being so reckless with our planet now, then I’m sure they’d behave differently, but they don’t know that, they don’t realize it.”
With books and podcasts, Dave and I try to spread that message the best we can. Dave says if each person who is already on board convinces one other person, and they each convince one other person, then it could snowball quite quickly.
It’s incumbent upon us to not just consume this information but to share it within our own spheres of influence.
As more politicians start to pay attention to environmental issues, climate change tops that list. “They haven’t really grasped the seriousness of biodiversity loss yet, but I think we’re getting there,” Dave says.
How We Can Each Combat the Insect Apocalypse
We can’t do anything about species that have already gone extinct, but for those species that are still hanging on after experiencing population decline, there is hope.
“Most of them are still with us in smaller numbers than they used to be, and they can recover pretty quick if we just give them somewhere to live, give them a bit of space, stop poisoning them,” Dave says.
There are simple things you can do in the garden in just a few days: Provide places for insects to live, some flowers to eat and someplace quiet to nest, and the insects will come. Those insects are food for birds and other wildlife, which will also come to your garden.
In the case of monarch butterflies, you can grow milkweed, the host plant for monarch caterpillars.
“Really simple stuff can transform a boring tidy garden into an absolutely amazing wildlife-rich habitat, and you can see it all happen and you can feel you’ve done your bit for the planet. And I think that’s really exciting,” he says.
What we refrain from doing — like refraining from using pesticides, putting down fertilizer, deadheading and mowing — also has a big impact. Dave gives the example of brownfield sites in London. These abandoned industrial sites were cordoned off because they were thought to be too toxic, but lo and behold, 20 years later they have become unintentional wildlife reserves in the absence of human intervention.
There are forces of resistance that are hard to overcome, such as homeowners associations that require lawns be mowed neatly and that herbaceous plants be cut back as soon as their flowers are spent. But when enough of us push the needle in the opposite direction, it will move.
If we as a society continue to ignore climate change, biodiversity loss and soil depletion, our future will not be sustainable. “We could easily lose half of life on earth within the next few decades,” Dave warns, noting that species are lost at the rate of one an hour.
“There’s no doubt at all we are right now in the sixth mass extinction event,” he says. “ Species are going extinct faster than they have for 65 million years since a meteor took out the dinosaurs.”
Earth is our home, providing us with food, water, beauty and inspiration. “It’s astonishing that we are being so careless with it,” Dave says.
I hope you enjoyed my conversation with Dave Goulson. If you haven’t listened yet, you can do so now by clicking the Play button on the green bar near the top of this post.
How have you changed your gardening practices to support insects? Let us know in the comments below.
Links & Resources
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“A Sting in the Tail: My Adventures with Bumblebees” by Dave Goulson
“A Buzz in the Meadow: The Natural History of a French Farm” by Dave Goulson
“Bee Quest” by Dave Goulson
“The Garden Jungle or Gardening to Save the Planet” by Dave Goulson
“Silent Earth: Averting the Insect Apocalypse” by Dave Goulson
“The Insect Apocalypse Is Here” from The New York Times
“The Little Things that Run the World” by E.O. Wilson
Disclosure: Some product links in this guide are affiliate links, which means we get a commission if you purchase. However, none of the prices of these resources have been increased to compensate us, and compensation is not an influencing factor on their inclusion here. The selection of all items featured in this post and podcast were based solely on merit and in no way influenced by any affiliate or financial incentive, or contractual relationship. At the time of this writing, Joe Lamp’l has professional relationships with the following companies who may have products included in this post and podcast: Rain Bird, Corona Tools, Milorganite, Soil3, Greenhouse Megastore, Territorial Seed Company, and TerraThrive. These companies are either Brand Partners of joegardener.com and/or advertise on our website. However, we receive no additional compensation from the sales or promotion of their product through this guide. The inclusion of any products mentioned within this post is entirely independent and exclusive of any relationship.