We live on a planet of insects.
They make up around 70% of all known species on the Earth,
and their combined biomass is 16 times that of humans.
300 million years ago,
giant dragonflies with wingspans of 75 centimetres
soared amongst the tree ferns.
Nowadays, insects are extraordinarily diverse,
existing in a bewildering array of colours, shapes and sizes,
and they play a crucial role in life on Earth.
They're food for a great many animals,
including most birds, bats, lizards,
amphibians and freshwater fish.
80% of the world's wild plant species depend on insects
to pollinate them,
as do three quarters of the plants we grow for food.
It's no exaggeration to say that without insects
many of us would starve.
But many types of insects around the world are in big trouble.
Although measuring insect populations is complex,
there are worrying signs.
A major 2020 study estimated that globally land-dwelling insects
are declining by about 9% per decade.
A German study found that the biomass of flying insects
on nature reserves fell by an alarming 76%
between 1989 and 2016.
In the United States, populations of the monarch butterfly
are down 80% this century.
Some species, such as the comma and speckled wood butterflies in the UK
are bucking the trend,
but the overall geographic range of butterflies in the UK
has contracted on average by 42% since 1976.
Invasive species also take their toll.
Rats ate the St Helena giant earwig to extinction
and have nearly exterminated the giant weta of New Zealand.
Light pollution also lures moths to bash themselves to death
and disrupts the timing of insect life cycles.
It also disorients some dung beetles who navigate
using the light of the Milky Way.
On top of all this, insects now have to cope with climate change.
Some adaptable insects, such as mosquitoes, cockroaches
and house flies, will benefit from warmer temperatures and more rain.
Most insects will suffer.
Bumblebees are disappearing from the southern edges
of their range,
overheating in their furry coats as the climate warms.
Droughts, floods and forest fires
will ravage already depleted insect populations.
In 1962, American biologist Rachel Carson wrote Silent Spring,
warning that we were doing terrible damage to our planet.
She wrote: "Man is a part of nature,
"and his war against nature
"is inevitably a war against himself."
But what she witnessed was just the beginning.
Since then, insect-rich wildlife habitats
have been destroyed on a vast scale.
Soils have been degraded and rivers choked with silt,
polluted or drained dry.
Farming, so reliant on insects for pollination, is responsible
for a large part of their decline.
An estimated four million tonnes of pesticides are released
into the global environment every year.
So what can we do if we want to protect our insects?
The obvious place to start is by rewilding our gardens
and balconies,
inviting insects in by planting wild flowers
and native shrubs,
reducing lawn-mowing and finding alternatives to pesticides.
But individual actions won't be enough.
Imagine green cities filled with trees, vegetable gardens,
ponds and unmowed verges,
all free from pesticides and buzzing with life.
A movement towards insect and nature-friendly
sustainable farming is growing,
but it needs much more support,
both from governments and consumers.
It's not quite too late.
Most threatened insect species have not yet gone extinct
and could quickly recover if protected.
American biologist Paul Ehrlich likened the loss of species
to randomly popping out rivets from the wing of an aeroplane.
Remove one or two, and the plane will probably be fine.
Remove ten or 20 or 50,
and at some point, there will be a catastrophic failure
and the plane will fall from the sky.
Insects are the rivets that keep the planet running.
How many can be safely removed from the plane before it crashes?