Where Have All Our Insects Gone?

monarch butterfly

Story at-a-glance -

  • They creep, crawl and fly, and some may even sting, but without a diverse population of insects, scientists agree the ecosystem will likely collapse
  • Research and anecdotal evidence concur: The population and diversity of insects on the earth has been rapidly declining in the past decades; many are on the brink of extinction
  • Although scientists are unable to pinpoint the cause, they believe the extent of the damage is likely the result of a variety of reasons, including insecticide use, light pollution, habitat fragmentation and climactic changes
  • You can help reestablish a diverse insect population by buying organic products, eliminating insecticide use in your yard and contacting your government representatives with your concerns

By Dr. Mercola

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, concluding,7 "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.8 Jack 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.11 He 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.

Crucial Consequences of Declining Insect Populations

While it may be difficult to get excited about combating the loss of insects, this ecological disaster may ultimately affect your food prices at the grocery store. One of the best illustrations of the ecological importance can be seen in bird populations. Without insects, many bird species face starvation and some believe this is already triggering serious declines and numbers.16 Wildlife author Michael McCarthy believes Britain's farmland birds have been cut in half since 1970, with some declines being outright catastrophic.

For instance, the spotted flycatcher, a specialist predator of aerial insects, has declined in number by more than 95 percent. The link between insects and the number of bird species was again confirmed in a study by the University of Aberdeen.17 Their data showed a drastic decline in cuckoo birds in some areas of England, closely linked to a similar decline in numbers of tiger moth caterpillars, one of the primary food sources for the cuckoo.

A study by Canadian biologists18 suggests bird species that depend on aerial insects have suffered a greater decline in recent years than birds feeding primarily on seeds.19 Germany's Federal Agency for nature conservation stresses insects are not only a major food source for birds, but also for bats and amphibians. Nearly 60 percent of birds rely on insects for food and 80 percent of wild plants depend on them for pollination.20

Tanya Latty, entomology teaching fellow at the University of Sydney School of Life and Environmental Sciences believes it's particularly worrying the declines have been reported in protected areas, meaning agricultural or urban areas may reveal an even more pronounced trend.21 She is also concerned we are underestimating the importance of insects, which make up approximately 70 percent of all animal species.

Insects not only pollinate the crops, but also contribute to pest control, and are crucial to waste management and biodiversity. In fact, Latty points out most waste in urban areas is eliminated by ants and cockroaches. Species that rely on insects as their food source, including predators that rely on these animals further up the food chain, are likely to suffer from the declining number of insects in the ecosystem.

One study estimates insects contribute $57 billion annually to the economy in the U.S., just through pollination, pest control, wildlife nutrition and dung burial.22 The drop in insect population is estimated to have far-reaching effects on the food economy, ecology and the future of the planet.

Multiple Reasons Behind Insect Armageddon

Each of the reasons theorized by scientists for the declining insect population have one common factor — they are all man-made, including urbanization, pesticides, pollution and changing climates.23 Entomologists believe it may also be related to rising sea levels and the elimination of plants critical for some insects to complete their development.24

Insecticides are designed to kill pests on crops. However, while they are intended to kill them directly on the plant, a special class of these chemicals — neonicotinoids — are believed to be a prime culprit behind mass die-offs of bees and butterflies. The chemical was partially banned in Europe in 2013,25 but remains one of the more popular insecticides in use, despite its history of compromising bee populations. The chemical affects the insects' memory and spatial skills, preventing them from finding food.26

Water-soluble pesticides can also leach out of the fields after they are applied to the crops,27 and have been found in high concentrations in nectar and pollen in wild flowers near treated fields. Although the levels are not sufficient to kill the insect directly, they affect their ability to navigate and communicate, and thus proliferate. The crops the insecticides are designed to protect, such as wheat and corn fields blanketing the U.S. Midwest, end up supporting almost no insect life at all.28

Although the team from Germany did not find evidence to support the hypothesis that habitat loss and climate change were important factors in the decline of insect populations,29 they did not look at large scale climate events such as prolonged droughts.

They were also unable to measure the effect of habitat fragmentation, which is different from reducing the overall amount of habitat available to the insects. Fragmentation can happen with small housing developments bordered by woods and fields on either side, or small agricultural plots.

Increasing urbanization may also expose flying insects to high levels of light pollution.30 Studies have already suggested artificial light at night has a negative impact on insects. Researchers have now discovered regions with high levels of light pollution at night have experienced a sharp decline in flying insects.

According to scientists from the Leibniz-Institute of Freshwater Ecology and Inland Fisheries, half of all insect species are nocturnal and depend on darkness and natural light from the moon for orientation, to escape predators and to seek food and reproduce. Artificial lighting disturbs this natural behavior and reduces their chances for survival. The researchers summarized their findings, saying:31

"Our overview study shows that artificial light at night is widely present and can have complex impacts on agricultural areas, with unknown consequences for biodiversity and crop production. Thus, light pollution should be generally considered as a potential ecosystem disturbance in future studies to identify ways in which practical steps can be taken to reduce environmental concerns."

Scientists See Some Populations Increasing While Others Decrease

Although most scientists are highly concerned by declining biodiversity and dramatic reductions in insect populations, some do not share concern over the critical nature of the unfolding events. Professor Helen Roy of the Center for Ecology and Hydrology retells success stories where insect populations have recovered, and she continues to be optimistic.32

Roy identified an explosion in the number of ladybirds and painted lady butterflies occurring in the past, as well as one study demonstrating some pollinators declined by 32 percent in one area while others became 16 percent more widespread. David Gibbons, from the Royal Society for the Protection of Birds,33 agrees not every investigation about insects reveals irrevocable decline, although he believes the overall picture is worrying.

However, while the proliferation of one species is heartening, it demonstrates an imbalance in biodiversity as others are rapidly declining. In much the same way the human gut microbiome requires balanced and diverse bacteria to function optimally, the ecosystem, built on a diverse population of insects, may not function well when one species gains a significant ecological advantage over another.

How You Can Help

There are several ways you can help to increase the population of insects:

Avoid insecticide use at home — While you likely have no direct control over insecticide use in agricultural concerns, you can control what you use in your own garden. Investigate natural methods to control specific pests, such as introducing natural insect predators, planting near other plants that are inhospitable to the pests or using mechanical methods such as diatomaceous earth.

Buy organic — How you spend your money has a big impact on farmers and large agricultural concerns. Businesses respond to their customers when their customers vote with their wallet. As more people purchase organically grown produce, more farmers will produce those products to meet the demand.

Since organic farmers do not use synthetic herbicides and pesticides and employ farming techniques designed to improve biodiversity across a wide spectrum, insect biodiversity is greatly improved and supported by organic farms.

Plant a garden — I think some of the best-tasting vegetables are those I can pick directly from my garden and eat the same day they are harvested. Even if you have a small yard or live in an apartment, there are many plants able to thrive in containers. In this way you also control what seeds you use and how you control pests and disease.

Contact your congressman or senator — Your government representatives are heavily lobbied by big agrichemical concerns. They also need to hear from you — the people they represent in government. Through a simple letter writing campaign in your area, you may be able to make a difference in the chemicals used, light pollution or the creation of insect-friendly habitats. Make it a habit to contact your congressman and your senator,34 and track their voting records.35