They creep along the ground, fly through the air and may sometimes sting you. It may seem as if the outdoor world has gotten more hospitable in recent years as the numbers of insects inhabiting your garden and splattering your windshield have drastically declined. However, reducing numbers and varieties of insects has a substantial overall impact on the environment and the future of the earth as we know it.
Entomologists from around the world are tracking the rapidly declining number of insects, and are concerned by the data they're collecting. As noted by the distinguished Harvard biologist Edward O Wilson, Ph.D.,1 "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."
These tiny and seemingly inconsequential bugs hold great power in plant pollination, soil microbial diversification, environmental cleanup and wildlife support. Insects are in a unique position to perform these functions in what appears to be a flawless and effortless fashion. Tragically, declines are now observed in many different insect populations. Overall diversification is also declining.
Insects Are in Serious Trouble
Since 1989, scientists from the Entomological Society Krefeld have collected insects in a nature preserve and along protected areas of western Germany.2 They use traps to collect specimens of local insects for research and education. Over the years, the team recognized the number of insects being collected each summer was getting lower and lower. Subsequently, the data from Krefeld was analyzed, finding a significant decline in the number of flying insects in western Germany.
Another study combined previous data and developed a global index for invertebrate abundance, showing a 45 percent decline over four decades. This study pointed out that of the 3,623 invertebrate species on the International Union for Conservation of Nature Red List, 42 percent are classified as threatened with extinction.3
What's more, from 1989 to 2016, the average weight of insects caught in Germany between May and October fell 77 percent. During the height of summer in those years, the weight of insects caught fell by 82 percent. Hans de Kroon, Ph.D., involved in analyzing the data said,4 "We were expecting declines, but the extent of them was tremendous. If this was in agricultural settings, we wouldn't be quite so surprised. But it's especially alarming that it's happening in nature reserves."
The data, published in the journal PLOS ONE, found the flying insect population in Germany's nature reserves had declined by more than 75 percent over the 27-year study. The researchers wrote the loss of diversity and abundance is expected to provoke a cascade effect on food supplies and jeopardize ecosystems.5 Evidence of the decline of individual species has been apparent for years. However, this study took a broad view of entire populations.
For instance, populations of European butterflies have been cut in half since 1990, honey bee colonies have been cut by 59 percent in North America since World War II and British moths have dropped by 30 percent per decade.6 The research group focused on the entire spectrum of flying insects, concluding7 "It confirms the widespread, windscreen phenomenon. Any truck driver in the developed world will tell you that they used to squash a lot of insects on the windscreen. Now the windscreen stays clean."
Australia and Great Britain Experience Similar Declines
Anecdotal evidence is also present in Australia and Great Britain, where scientists have noted a decline in insect population but are at a loss in determining the cause.8Jack Hasenpusch is an entomologist and owner of the Australian Insect Farm,9 where he collects swarms of wild insects during the summer months. He noticed that in the past few years some insect varieties have dropped off and he attributed this to a lack of rainfall.
However, the reduction in insect population has continued to fall. Hasenpusch reports speaking to entomologists in Sydney, Brisbane, Perth and Italy, all telling similar stories.10 University of Sydney entomologist Cameron Webb primarily researches mosquitoes and reports their numbers are also declining across New South Wales.11He believes this is indicative of the situation with other insect populations.
Without formal research, it is difficult to make accurate predictions or assessments about the numbers of insects in Australia. However, Webb believes it's important to listen to entomologists, ecologists and other researchers who are in the field on a regular basis. He commented:12
"I don't study cicadas, but I know what cicada numbers are like from year to year because I'm out and about in my local wetlands. When experts are relaying this kind of information it is something that we need to turn our mind to and think about what could be going on, and more importantly how do we work out if this is actually happening and what we do about it."
Similar reductions in insect populations are being reported from Great Britain. Chris Packham,13 naturalist, conservationist and TV presenter, recently took to Twitter, commenting on the absence of insects during a weekend at his home. Packham tweeted he had not seen a single butterfly in his garden and rarely sees craneflies or moths, which were commonplace when he was a boy. He wrote,14 "Our generation is presiding over an ecological apocalypse and we've somehow or other normalized it."
In Great Britain, populations of native ladybirds are crashing, three-quarters of butterfly species have dropped in numbers and bees are suffering major declines in population.15 Cicadas, beetles and moths also face some of the same challenges, with the V-moth recording a 99 percent fall in numbers between 1968 and 2007, according to The Guardian. It's now threatened with extinction.