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| Light traps have long been used to monitor nocturnal insect numbers. In a photograph of one taken in 1978, about 3,000 species were identified. Photograph: Patrick Greenfield/The Guardian |
This is one of the most depressing and dispiriting pieces I've seen in a long time.
From The Guardian. Lightly edited]
In front of him was a world seething with life. Every branch of every tree seemed to host its own small metropolis of creatures hunting, flying, crawling, eating. The research facility lay in a patchwork of protected rainforest, dry forest, cloud forest, mangroves and coastline covering an area the size of New York, and astonishingly rich in biodiverse life. Here, the bugs gorged, coating the leaf litter with a thick carpet of droppings.
But the real show was at night: for two hours each evening, the site got power and a 25-watt bulb flickered on above the porch. Out of the forest darkness, a tornado of insects would flock to its glow, spinning and dancing before the light. Lit up, the side of the house would be “absolutely plastered with moths – tens of thousands of them”, Janzen says.
Inspired, he decided to erect a sheet for a light trap with a camera – a common way to document flying insect numbers and diversity. In that first photograph, taken in 1978, the lit-up sheet is so thickly studded with moths that in places the fabric is barely visible, transformed into what looks like densely patterned, crawling wallpaper.
Scientists identified an astonishing 3,000 species from that light trap, and the trajectory of Janzen’s career was transformed, from the study of seeds to a lifetime specialising in the forest’s barely documented populations of caterpillars and moths.
Now 86, Janzen still works in the same research hut in the Guanacaste conservation area, alongside his longtime collaborator, spouse and fellow ecologist, Winnie Hallwachs. But in the forest that surrounds them, something has changed. Trees that once crawled with insects lie uncannily still.
The hum of wild bees has faded, and leaves that should be chewed to the stem hang whole and un-nibbled. It is these glossy, untouched leaves that most spook Janzen and Hallwachs. They are more like a pristine greenhouse than a living ecosystem: a wilderness that has been fumigated and left sterile. Not a forest, but a museum.
Over the decades, Janzen has repeated his light traps, hanging the sheet, watching for what comes. Today, some moths flutter to the glow, but their numbers are far fewer.
“It’s the same sheet, with the same lights, in the same place, looking over the same vegetation. Same time of year, same time of the moon cycle, everything about it is identical,” he says. “There’s just no moths on that sheet.”
The declines witnessed by Janzen – and described by others around the world – are part of what some ecologists call a “new era” of ecological collapse, where rapid extinctions occur in regions that have little direct contact with people.
Reports of falling insect numbers around the world are not new. International reviews have estimated annual losses globally of between 1% and 2.5% of total biomass every year.
Widespread use of pesticides and fertilisers, light and chemical pollution, loss of habitat and the growth of industrial agriculture have all carved into their numbers. Often, these were deaths of proximity: insects are sensitive creatures, and any nearby source of pollution can send their populations crumbling.
But what Janzen and Hallwachs are witnessing is a part of a newer phenomenon: the catastrophic collapse of insect populations in supposedly protected regions of forest. “In the parts of Costa Rica that are heavily hit by pesticides, the insects are completely wiped out,” Hallwachs says.
“But what we see here in the preserved areas – that as far as we can tell, are free of even these destructive insecticides and pesticides – even here, the insect numbers are going down horrifyingly dramatically,” she says.
Long-term data for insect populations – particularly less charismatic species – is still patchy, but Janzen and Hallwachs join a number of scientists that have recorded huge die-offs of insects in nature reserves around the world.
They include in Germany, where flying insects across 63 insect reserves dropped 75% in less than 30 years; the US, where beetle numbers dropped 83% in 45 years; and Puerto Rico, where insect biomass dropped up to 60-fold since the 1970s. These declines are occurring in ecosystems that are otherwise protected from direct human influence.
When David Wagner stepped out into the US’s southern wilderness this spring, he found landscapes emptied of life. The entomologist has devoted much of his career to documenting the vast diversity of US insect life, particularly rare caterpillars. He traverses the country to find specimens, often on long road trips searching for caterpillars by day and moths by night.
Now, he finds himself coming home empty-handed. “I just got back from Texas, and it was the most unsuccessful trip I’ve ever taken,” he says. “There just wasn’t any insect life to speak of.”
It was not only the insects missing, he says, it was everything. “Everything was crispy, fried; the lizard numbers were down to the lowest numbers I can ever remember. And then the things that eat lizards were not present – I didn’t see a single snake the entire time.”
Wagner recalls when a series of international reviews began hitting headlines in 2019, saying global insect biomass was declining at a rate of 1% a year (although some estimates put it as high as 2.5%).
“We [entomologists] were thinking conservatively,” he says, looking at the data that has emerged in the five years since then.
“I now think that that’s too low. Now I would say that 2% is happening in some areas, and we’re seeing some places threatened by climate change or urbanisation or agriculture get as high as 5% decline per year.”
Those who doubt there is sufficient species data to prove the “insectageddon” can now track it by proxy, Wagner says: via the sharp declines in birds, lizards and other creatures that depend on them for food.
Scientists in the US, Brazil, Ecuador and Panama have now reported the catastrophic declines of birds in “untouched” regions – including reserves inside millions of hectares of pristine forest. In each case, the worst losses were among insectivorous birds.
At one research centre – falling within a 22,000-hectare (85 sq mile) stretch of intact forest in Panama – scientists comparing current bird numbers with the 1970s found 70% of species had declined, and 88% of these had lost more than half of their population.
In 2019, researchers found that almost a third of US birds – about 3 billion – had disappeared from the skies since the 1970s. The losses, however, were not evenly distributed: those birds that ate insects as their main food had declined by 2.9 billion. Those that didn’t depend on insects had actually gained, increasing by 26 million.
More recent research from the US found a decline in three-quarters of nearly 500 bird species studied – with the steepest downward trend in stronghold areas, where they once thrived.
In Puerto Rico’s Luquillo rainforest, scientists in 2018 mapped how the loss of insects set other dominoes falling: as bugs declined, so too did the populations of lizards, frogs and birds. Their disappearance, they wrote, had triggered “a bottom-up trophic cascade and consequent collapse of the forest food web”.
In Costa Rica, Janzen described the fall in numbers of insectivorous birds in the reserve as “cratering”. A colony of about 20 nectar-eating bats have long nested in the dark nooks of Janzen and Hallwachs’ house, but Janzen has noticed the flowers they used to feed from are now failing to bloom.
Hallwachs began to find their small, emaciated bodies lying on the floor. “Over a period of five days, I found three of these bats dead,” she says. Researchers at another site 20 miles away told her they were witnessing the same thing.
Behind the steepening declines, a clear culprit is beginning to emerge: global heating. A tropical forest ecosystem is “a finely tuned Swiss watch”, Hallwachs says – perfectly engineered to sustain a vastly biodiverse system of creatures.
Each element is delicately tuned and interlocks with the rest: the heat, the humidity, the rainfall, the unfolding of leaves, the length of the seasons, the start and stop of the life cycles of insects and animals.
With each incremental turn of one cog, the rest of the system responds. Insects and animals have evolved to time their hibernations and breeding times precisely to small signals from the system: a change in humidity, a lengthening of the light hours of the day, a small rise or fall in temperature.
But now, the system has one gear spinning wildly out of time: the climate.
“When I arrived here in 1963 the dry season was four months. Today, it is six months,” Janzen says. Insects that typically spend four months underground, waiting for the rains, are now forced to try to survive another two months of hot, dry weather. Many are not succeeding.
Alongside the changing seasons are other shifts, such as in rainfall or humidity. “It’s just a general disruption of all the little cues and synchronies that would be out there,” Janzen says. Across the entire clock of the forest, plants and creatures are falling out of sync. In the background, the temperature is rising.
“The killer – the cause that’s pulling the trigger – is actually water,” says Wagner. For insects, staying hydrated is a unique physiological challenge: rather than lungs, their bodies are riddled with holes, called spiracles, that carry oxygen directly into the tissue.
“They’re all surface area,” says Wagner. “Insects can’t hold water.” Even a brief drought lasting just a few days can wipe out millions of humidity-dependent insects.
[Read more here.]
Already, alternating droughts, floods and heatwaves are affecting the production of food. But without insects, there will be no food. Mankind is too stupid, too greedy, and too ignorant, to stop the processes that are leading to the destruction of the Earth and of ourselves. We could stop emissions which cause global heating and catastrophic collapses in insect populations. But we do not. We could reduce or even stop using pesticides and insecticides. We do not. We could stop producing plastics in the quantities we do. But we don't.
Meanwhile, it's not just insects which are dying, but also the seas.
Millionaires, billionaires and large corporations control our politics, and they stop our politicians taking action on global heating, insecticides, and plastics.
If you think that is too pessimistic a view, consider that Australia's Labor Party has just won a landslide in an election, wiping out the right-wing, anti-climate L/NP coalition. A key difference between Labor and the L/NP was, supposedly, their different attitudes to climate change. Yet, as soon as the election was over, it approved a massive expansion in the life of a gas extraction and exporting facility in NW Australia. The emissions from the extension of this project alone will produce another 6 billion tonnes of greenhouse gases. Australia's total CO2 emissions in 2023 were 383 million tonnes. I needn't even discuss the situation in the USA. And even in countries which purport to do something about climate change, fossil fuel subsidies continue. We're encouraging people to destroy us and our civilisation.
I despair.
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