The meadows are no longer buzzing, and our gardens are falling silent. We spoke to Prof Dave Goulson, a professor of biology at the University of Sussex, about why our insects are in decline and how we can help bring them back.
Dave has been obsessed with insects all his life. He’s spent almost 30 years specialising in bumblebees and founded the Bumblebee Conservation Trust. He has written a number of popular science books, including his latest, Silent Earth: Averting The Insect Apocalypse (£20, Jonathan Cape).
Why are insects important, and what roles do they play in the ecosystem?
So many, it’s hard to know where to start. Insects make up the bulk of life on Earth in terms of biodiversity. More than two-thirds of all species that we’ve identified are insects. Birds, other insects, bats, lots of small mammals, lizards and freshwater fish all depend on insects for food. If the insects weren’t there, then they wouldn’t be there.
But insects do a whole bunch of other important stuff too. Scientists call it ‘ecosystem services’, which is a bit of an unhelpful phrase. It’s things like recycling, so maggots help to get rid of dead bodies, dung beetles help to get rid of cowpats, and other insects help to break down dead trees and leaves and other things. So they’re really important in nutrient cycles. They keep the soil healthy. They move seeds around. They do all sorts of stuff.
I guess the thing that most people recognise is that insects pollinate. So roughly 87 per cent of all the plant species on the planet need pollinating by some kind of animal – occasionally, in the tropics, that animal is a hummingbird or a bat. But 99 per cent of the time it’s some kind of insect.
Essentially, life on Earth would grind to a halt if we didn’t have insects.
There are large numbers of insects dying out. Why is that?
There are many drivers. You know, there’s no single cause of insect declines, but probably the biggest one has been loss of habitats in the UK, things like our ancient woodlands, our heathlands, our fens and marshes, and our flower-rich meadows – most of them have been swept away. Obviously this isn’t something that’s confined to the UK. In the tropics, we’ve got deforestation and so on.
Essentially, we’re replacing natural, biodiverse habitats with cities or monocultures of crops and that’s had a huge impact. And associated with that is probably the second biggest driver of insect declines, which is the rise in the many different pesticides we use in farming, but also in gardens and in our streets.
But then there’s a whole bunch of other things, such as invasive species, climate change, light pollution affecting nocturnal moths and so on. It’s almost like a sort of perfect storm. You know, insects might cope with one or two things, but they can’t cope with this whole blizzard of different adverse pressures on their populations.
I remember when I was child, if you went for a drive in the car there would be bug splats all over the windscreen. I don’t see that any more.
I’ve heard this from so many people, and it’s the only aspect of insect declines that’s really in the public consciousness. You know, people don’t pay much attention to insects – most people aren’t regularly looking out for them. But there was this phenomenon of having to stop to clean your windscreen, which I can remember from when I was younger.
There was a time a few decades ago where the windscreen, the headlights, the grille and the whole front of the car was this mass of dried, splattered insect guts. And it just doesn’t happen at all any more.
There is an interesting theory that it might be related to the aerodynamics of cars, because obviously cars are more streamlined than they used to be and that seemed to be quite a plausible – or at least partial – explanation. So, Kent Wildlife Trust did a study where they recruited volunteers with different aged cars to record the number of splats on them. And actually, they found that even people driving around in classic cars that are much less aerodynamic don't have any splats on their windscreens either. So that isn't the explanation, it turns out.
Are we seeing these declines in insects all over the world?
The long-term insect studies are biased towards Europe and North America, where there are lots of scientists, like me, that are interested in insects. We have almost no data from Africa, South America and most of Southeast Asia, which is really worrying because that’s where most biodiversity is.
There were one or two studies from the tropics, which show pretty big insect declines, but for most tropical insects, we haven’t really got any data. I’d be pretty confident that they’re declining there, too, because we’re seeing massive habitat loss and climate change and all these other environmental issues affecting those countries.
What will happen if we lose the insects? What will the future look like?
Life will be tough. Most of the fruits and vegetables we eat depend upon insects to give a good harvest. So if we lose pollinators, then it’s going to be really difficult to provide a healthy diet to the growing human population.
But it isn’t just pollination. I mentioned earlier that insects help to keep the soil healthy; we have major problems with soil degradation around the world. Soil health depends on all the little creatures that live in it and we need healthy soils to grow crops. We also need insects to recycle things like cow dung. It’s absolutely vital that all the nutrients in cow dung get recycled.
There’s actually a really interesting example of the importance of that. When we colonised Australia and we took cattle, there were no dung beetles in Australia that could cope with cow dung, as they were used to marsupial dung, which is really dry. The cowpats weren’t being removed and were just drying into hard little plates. Eventually, the entire landscape was covered in a layer of cowpats and the grass couldn’t go grow through.
At one stage, 15,000km2 of Australia was covered under dried cowpats. And so they introduced dung beetles able to cope with cow dung. That was one example of a very successful introduction. Some animal introductions have gone badly wrong, but the dung beetles that were introduced ate all the dung and now the grass is doing well, the nutrients are being recycled.
It just shows that we take it for granted that the insects are there and they’re doing these things. And if they’re not there, then that’s when we notice the problems.
Read more about insect conservation:
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- Can we save the insects?
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Do we know how many insects are still out there waiting to be discovered?
We’ve named 1.1 million species of insect so far, roughly. We find new ones every day. There are undoubtedly lots we haven’t yet described, or haven’t given any kind of name to. But scientists struggle to estimate exactly how many there are.
People have tried to estimate, and most of the predictions suggest that there are somewhere between a million and 10 million more insect species that we haven’t yet named. Obviously, that’s a huge range, so it’s probably a more realistic to say there are four or five million more species.
But that means that we’ve only named about 20 per cent – it’s absolutely astonishing that there are all these amazing creatures out there that we’ve yet to discover.
Is there anything we can do in our day-to-day lives to help the insects?
You see these environmental issues, like the rainforest burning and you feel helpless. It’s depressing. You wonder, “What on Earth can I do to help?” But with insects it’s different. They live in our gardens and local parks and in the road verges and, you know, they’re everywhere. And even small things really do make a difference in the end. Most insects, thankfully, haven’t yet gone extinct, and they can breed really fast, so if you provide the right conditions for them, their populations recover quickly, unlike pandas or tigers.
The obvious place to start, if you’re lucky enough to have a garden, is to grow lots of bee-friendly and pollinator-friendly flowers. Grow some wildflowers, don’t mow your lawn too much, and plant some flowering trees if you’ve got a big enough garden. A pond will support a whole range of insect life. A little bee hotel will work quite well for some solitary bees. Don’t use any pesticides. It seems crazy to me that we spray poisons in our gardens and the councils spray them in our streets and so on.
Most things you can do are really simple and many of them involve doing less rather than more, like less mowing of your lawn, less spraying of pesticides, not being so tidy, allowing a few weeds to flower. And little things like these really do make a difference.
There are 22 million private gardens in the UK. So just imagine if most of them were insect- and wildlife-friendly. That would really make a difference. It would be kind of a national network of little patches of miniature nature reserves. That would be fantastic.
Many people dislike insects, and say, “What’s the point in a wasp? What’s the point in a mosquito?” Is there any way we can change people’s minds on that?
Well, I often say, “What’s the point of people?”
There are different ways of trying to persuade people that insects deserve looking after. You can use the argument that they’re important – they often do things that are valuable to us, even if we might not recognise them. Wasps, for example, are effective pollinators – many people don’t realise that. They’re also really good at pest control, they eat aphids and caterpillars on our crops.
But there are probably some insects that don’t do anything useful at all and you can’t create an economic, utilitarian argument to save them. But I think it’s really sad to bring everything back to a species only being worth saving if it does something for us. It’s incredibly selfish. These are creatures that have been on the planet for millions of years – much, much longer than we have. And, you know, whether they do something useful or not, whether we find them beautiful or not, surely they have as much right to be here as we do?
We should try to be more tolerant of nature and value it for its own sake. We live on this rock hurtling through space with a little crust of life clinging to its surface. I mean, the whole thing is absurd and unbelievable, really.
As far as we know, there may be no other life in the Universe, or it may be so far away that we never encounter it – and certainly nothing like [the life here on] Earth. It’s unique. It’s our home. It gives us everything we could want. You know, it’s beautiful. It’s inspirational. It feeds us and all the rest of it. And we’re not really looking after it terribly well.
And I find that just completely extraordinary. How stupid are we that we don’t look after our home and all of the creatures that live on it? All our fellow travellers on this rock hurtling through space, we should value them.
These little creatures deserve to live. I just think they’re amazing, actually. The more time you spend looking at insects, the more you realise how fascinating and intriguing they are and how much there is we don’t know about them, and we’ll never know if we wipe them all out. There are all these millions of insects we haven’t even discovered yet; who knows what secrets they have?
I find it terribly sad, the thought that there are species going extinct that we haven’t even seen. Species that we’ll never know existed – because they’ll be gone. And that seems like a terrible thing.
- This article first appeared inOctober 2021ofBBC Science Focus Magazine–find out how to subscribe here
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