by Robin McKie
The European oil beetle,
many insect species under threat in the UK.
Photograph: Alfred Schauhuber
a crisis in the countryside
- and a massive
decline in insect numbers
When Simon Leather was a student in the 1970s, he took a
summer job as a postman and delivered mail to the villages of Kirk
Hammerton and Green Hammerton in North Yorkshire.
He recalls his early
morning walks through its lanes, past the porches of houses on his
At virtually every home,
he saw the same picture:
with tiger moths that had been attracted by lights the previous
night and were still clinging to the glass.
"It was quite a
sight," says Leather, who is now a professor of entomology
at Harper Adams University in Shropshire.
But it is not a vision
that he has experienced in recent years. Those tiger moths have
"You hardly see any,
although there used to be thousands in summer and that was just
a couple of villages."
It is an intriguing story
and it is likely to be repeated over the next few weeks.
The start of summer is
the time of year when the nation's insects should make their
presence known by coating countryside windows with their fluttering
presence, and splattering themselves on car windscreens. But they
are spectacularly failing to do so. Instead they are making
themselves newsworthy through their absence.
Britain's (and worldwide) insects, it
seems, are disappearing.
This point was underlined last week when
tweets from the naturalist and TV presenter
Chris Packham went viral after he commented on the absence of
insects during a weekend at his home in the New Forest.
Packham said he had not
seen a single butterfly in his garden, and added that he sleeps with
his windows open but rarely finds craneflies or moths in his room in
By contrast, they were
commonplace when he was a boy.
"Our generation is
presiding over an ecological apocalypse and we've somehow or
other normalized it," he later said.
Certainly, the statistics
populations are crashing; three quarters of
butterfly species - such
as the painted lady and the Glanville fritillary - have dropped
significantly in numbers; while bees, of which there are more than
250 species in the UK, are also suffering major plunges in
populations, with great yellow bumblebees, solitary potter flower
bees and other species declining steeply in recent years.
Other threatened insects
include the New Forest cicada, the tansy beetle and the oil beetle.
As for moths, some of the most beautiful visitors to our homes and
gardens, the picture is particularly alarming.
Apart from the tiger
moth, which was once widespread in the UK, the V-moth (Marcaria
wauaria) recorded a 99% fall in numbers between 1968 and 2007 and is
now threatened with extinction, a fate that has already befallen,
A great yellow bumblebee.
Its numbers have declined steeply in recent years.
An insect Armageddon is under way, say many entomologists, the
result of a multiple whammy of environmental impacts:
changes, overuse of pesticides, and
And it is a decline that
could have crucial consequences.
Our creepy crawlies may
have unsettling looks but they lie at the foot of a wildlife food
chain that makes them vitally important to the makeup and nature of
"the little things
that run the world",
...according to the
distinguished Harvard biologist Edward O. Wilson, who once
"If all humankind
were to disappear, the world would regenerate back to the rich
state of equilibrium that existed 10,000 years ago. If insects
were to vanish, the environment would collapse into chaos."
The best illustration of
the ecological importance of insects is provided by our birdlife.
Without insects, hundred
of species face starvation and some ornithologists believe this lack
of food is already causing serious declines in bird numbers, a point
stressed by the naturalist and wildlife author Michael McCarthy.
birds have more than halved in number since 1970," he points
"Some declines have
been catastrophic: the spotted flycatcher, a specialist predator
of aerial insects, has both declined by more than 95%, while the
red-backed shrike, which feeds on big beetles, became extinct in
Britain in the 1990s."
Further confirmation of
the link between insect and bird numbers was provided last week with
the publication of a study (Breeding
ground correlates of the distribution and decline of the Common
Cuckoo Cuculus canorus at two spatial scales) by Aberdeen University researchers which
showed that the plunge in numbers of cuckoos in some areas of
England was closely linked to declines in tiger moth caterpillars on
which cuckoos feed.
"There is now a lot
of correlational evidence to show that when certain insects do
badly, very often the birds that feed on them get into trouble
as well," said David Gibbon, of the RSPB.
However, insects also
play invaluable roles in other parts of the environment - for
example as pollinators of our orchards and fruit fields.
And again, scientists are
"People think that it
is just bees that pollinate orchards, but there are huge numbers
of flies that also pollinate - and they are all also
threatened," said Leather.
In addition, flies,
beetles and wasps are predators and decomposers who control pests
and who generally clean up the countryside.
"Just think of the
work of the dung beetle," added Leather. "If they go, the land
would be covered with the excrement of cows, sheep and other
The tansy beetle, which
is 'nationally rare', is the subject of a major conservation program
The tansy beetle,
which is 'nationally rare',
is the subject of a major
conservation program in Yorkshire.
But perhaps the most alarming indication of the ecological
apocalypse we face was provided a few months ago by researchers who
published a startling paper (More
than 75 percent Decline over 27 Years in total Flying Insect Biomass
in protected Areas) in the journal Plos One
Their work was based on
the efforts of dozens of amateur entomologists in Germany who began
employing strictly standardized ways of collecting insects in 1989.
They used special tents
called malaise traps to capture thousands of samples of insects in
flight over dozens of different nature reserves.
Then the weight of the insects caught in each sample was measured
and analyzed - revealing a remarkable pattern. The annual average
weight of insects found in the traps fell by 76% over the 27-year
period of their research.
Most alarming, however,
was the discovery that the decrease was even higher - 82% - in
summer, a time when insect numbers should reach their peak.
Such figures give strong numerical support to the veracity of
anecdotes about splattered car windscreens and moth-plastered patio
windows becoming a thing of the past. Equally stark is the fact that
although meteorological patterns fluctuated to some degree during
the years of the study, it was clear that weather was not the cause
of the declines.
But perhaps the most alarming aspect of the research was the
realization that these grim drops in insect numbers were occurring
in nature reserves - in other words, in areas where the landscape
was highly protected and should be the most friendly of habitats for
Conditions elsewhere were
likely to be a lot worse, the scientists warned.
"Insects make up
about two-thirds of all life on Earth [but] there has been some
kind of horrific decline," Professor Dave Goulson of Sussex
University, said at the time.
"We appear to be
making vast tracts of land inhospitable to most forms of life,
and are currently on course for ecological armageddon. If we
lose the insects, then everything is going to collapse."
The fact that insect
biomass has been declining at a steady rate for almost three decades
strongly suggests some profound influences must be at work.
believe habitat change lies at the heart of the problem.
"There have been
massive alterations to the way we use the land and it is hard
not to believe these are closely involved in what we are
seeing," said Leather.
As he points out,
intensively farmed wheat and cornfields support virtually no insect
life, and this means that as intensive agriculture spreads there are
fewer and fewer islands of natural habitat left to support them.
A garden tiger moth caterpillar.
Changes in habitat caused by intensive farming
have been blamed for the decline
of insect populations.
Photograph: H Lansdown/Alamy
And then there is the issue of urban spread.
Housing schemes continue
to encroach on our woods and heaths so that streets and buildings
generate light pollution that leads nocturnal insects astray and
interrupts their mating.
"That is the reason
we see most changes to insect life in south-east England, for
that is where we see the greatest spread of cities and towns,"
In addition to habitat
changes, there are the dangers posed by pesticides, in particular
neonicotinoid pesticides, which have already been blamed for recent
crashes in bee populations. These chemicals are water soluble and so
leach out of fields after they are applied to crops.
According to research quoted in the journal Science last year, these
pesticides have since been found in high concentrations in nectar
and pollen in wildflowers near treated fields.
Though still not at
levels sufficiently high to kill insects directly, they do affect
their abilities to navigate and communicate.
In the face of this mixture of ecological woes, it is perhaps not
surprising that insects in Britain are faring so badly. Whether or
not they face an ecological apocalypse is a different matter, for
not every expert shares a sense of doom.
Professor Helen Roy
of the Centre for Ecology and Hydrology, for example, sees cause for
She told the Observer
that there were too many success stories - tales of insects that
were recovering in numbers and thriving - to feel a sense of
species are suffering, but I am an optimist and I just don't
think it is right to call this an apocalypse," she said.
Roy pointed to explosions
in the number of ladybirds and painted lady butterflies that have
occurred in the past as evidence.
"There are huge
variations in numbers of a particular insect species in a year
and huge variation in the places you see them."
She also pointed to one
study of pollinators that showed while 32% became less widespread
between 1980 and 2014, 16% became more widespread.
"It is not all doom
and gloom," Roy added.
This view was supported
by David Gibbons of the RSPB who agreed that not every
investigation about insect numbers revealed a tale of irrevocable
decline - though he added that he still believed the overall picture
"It is hard not to
see a link between some of the bird number declines and drops in
insect populations we are experiencing. There are very close
correlations in many cases.
But proving there is
a causative link - in establishing the one effect is leading to
the other - is much more difficult."
We appear to be making
tracts of land inhospitable to most forms of life. If we lose
insects, it all collapses
An illustration of the problem is provided by one of the few cases
where a causative link between insect loss and bird-number declines
has been established: the grey partridge, Gibbons said.
"During the 70s and
80s, pesticides were killing off plants on which sawflies and
other insects fed.
Grey partridge chicks
feed on these insects and so this process led to a decline in
their numbers - and that has since become dramatic."
In fact, the grey
partridge's drop in numbers has brought its population to less than
5% of its figure last century.
The crucial point is that researchers were able to show that these
twin declines were connected by manipulating herbicide levels in
places where chicks were being reared.
When herbicide levels
went up, insect levels went down and so did bird numbers.
provided the causative link," said Gibbons. "It was possible to
change insect numbers and so see the impact. However, such
research is difficult to carry out and is very rare."
And of course, threats to
our birdlife are only one aspect of the dangers posed by losses of
insects in the UK.
As entomologists point
out, they also keep our soil fertile, degrade waste, pollinate our
orchards and control pests such as the aphid.
"We cannot afford to
lose them and that's what makes this issue so urgent and so
important," Leather concluded. "That's worth keeping in mind as
the summer evenings begin - and we see hardly any insects."
Many of Britain's native species of ladybirds are suffering
serious declines in numbers, thanks to the arrival of the
It has been declared
the UK's fastest invading species, after reaching almost every
corner of the country in just a decade.
It preys on native
ladybirds and is believed to have caused the decline of at least
seven species, including the popular two-spot ladybird, which -
when last assessed in 2012 - had slumped by 44% in numbers.
More than 2,500 moth species have been recorded in Great
Britain, of which around 900 are called larger moths.
In the report The
State of Britain's Larger Moths 2013, it was revealed that
larger moths had declined by 28% between 1968 and 2007. This was
most noticeable in southern Britain where there was a 40%
By contrast, numbers
showed no significant change in northern Britain, where
disappearing species are balanced by moths spreading north
because of climate change.
Seventy of the 100 crop species that provide 90% of food
worldwide are pollinated by bees.
In the UK, there are
more than 250 species of bee:
25 species of
bumble bee, 224 species of solitary bee and one honey bee
According to a
government report in 2014, figures there has been
an overall decline in wild and honey bees
over the past 50 years.
The figures also
revealed evidence that there has been parallel declines in the
plants that rely on them for pollination.
The State of the UK's Butterflies report - produced in 2015 by
Butterfly Conservation - provided further evidence of,
long-term and ongoing decline of UK butterflies".
Overall, 76% of the
UK's resident and regular migrant butterfly species had declined
in either abundance or occurrence (or both) over the past four
decades, it was found.
"This is of great
concern not just for butterflies but for other wildlife
species and the overall state of the environment," the
These insects eat large volumes of slugs and aphids and large
numbers of weed seeds, thus helping to stop fields being overrun
by unwanted plants and pests.
However, a study,
published in the Journal of Applied Ecology in 2012 - which
looked at 68 beetle species at 11 locations around the British
Isles over 15 years - found that three-quarters of those
examined had declined in number over the period.
Of these, half had
fallen at rate equivalent to 30% per decade.