My article for the Telegraph:On Twitter this week an unfortunate hiker showed a short video of the midges swarming in their tens of thousands over his backpack and his arms in the Scottish Highlands. It was itchy just to watch. It would be silly to argue that his video is evidence that insects are increasing in number. Yet the evidence for a dramatic decline in insect numbers, an “insect apocalypse”, which activists and journalists have been proclaiming recently, is about as weak as such a claim would be.
A film called Insect O Cide is coming out soon. Its ludicrous central theme is that “human beings are on the verge of extinction due to the rapid decline in the insect populations”. “The Insect Apocalypse is here”, said the New York Times in 2018. “Plummeting insect numbers ‘threaten collapse of nature’” said the Guardian in 2019. The source for this claim was a paper published in the journal Biological Conservation by two Australian scientists that claimed to reveal “dramatic rates of decline that may lead to the extinction of 40 per cent of the world’s insect species over the next few decades”.
This was junk science of the worst kind. As three other scientists then pointed out, “there is so much wrong with the paper, it really shouldn’t have been published in its current form: the biased search method, the cherry-picked studies, the absence of any real quantitative data to back up the bizarre 40 per cent extinction rate that appears in the abstract … and the errors in the reference list.” Of the studies cited by the apocalypse paper, the three said, “we were really surprised to discover how many of them we had to discard, because they contained no data”.
But whereas the apocalypse paper was rushed through peer review to publication and movie hype in four months, the debunking paper pointing out its “exaggerated and unlikely narrative” was held up for 12 months by hostile reviewers trying to get it killed. This imbalance in scientific publishing and media coverage is common: alarming results get megaphoned, moderate ones are muttered.
Two previous papers claiming to find declining insect numbers, in Germany and Puerto Rico respectively, were even less persuasive. The German one compared different sites at different times, sampled some locations only once, and used a mathematical model to extract a “result”. The widely repeated claim some years ago that honey bees were dying out was false: global populations are increasing. Reports of vanishing bumblebees in Britain are also wide of the mark. Tree nesting species have increased, while some ground-nesting ones have declined partly because of increased badger predation. Others are holding their own.
As for the anecdotal claim, repeated even by Jeremy Clarkson in his Amazon series on farming, that fewer insects blot your windscreen these days, well, the politest thing you can say is that it’s unsubstantiated. I dare say on a crowded motorway there are somewhat fewer flattened flies on my windscreen these days, but then several thousand cars in front of me have mostly swept them up already. There are more cars on the road to share the work.
About a million species of insects have been given names by scientists, and many more remain undescribed. Some of those species and their ecological niches are in trouble, others are thriving. As the lead author of the debunking paper, Manu Saunders, put it, “sensationalising geographically and taxonomically limited studies as evidence of global patterns may grab attention but can also have unwanted side effects. In particular, doom and gloom messaging rarely works to galvanise public support and strong negative messaging (e.g., apocalypse narratives) can undermine the credibility of science, especially as more facts become available.” Keep crying wolf and you might not be believed next time.
Of the million species described, have a guess how many are known to have gone extinct, according the official Red List of the International Union for the Conservation of Nature. It’s 63. That’s not 40 per cent or 4 per cent or 0.4 per cent, or 0.04 per cent: it’s more like 0.004 per cent. Most of those were on islands, which means invasive species probably caused their extinction, and of those for which a “last seen” date is given, the majority disappeared more than a century ago. Only six have a post-war “last seen” date, and the most recent is 1975.
Sure, many others must have died out unnoticed and more are no doubt teetering on the brink. But in other ways the list may exaggerate the rate of extinction. Take Ridley’s stick insect, known only from one specimen collected in 1907 in Singapore by some namesake of mine. It’s presumed extinct, but are we even sure it was a species rather than a slightly unusual individual of another species?
The flower meadow I planted a few years ago is this week alive with spectacular insects, from bumblebees, butterflies and damselflies to a splendid longhorn beetle called Leptura quadrifasciata and a stunning little ichneumon with a long ovipositor called Ephialtes manifestator. Rather than make baseless claims about an insect apocalypse, we should love and help these astonishing and diverse creatures.
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