Insect apocalypse? Not so fast, at least in North America

In recent years, the notion of an insect apocalypse has become a hot topic in the conservation science community and has captured the public’s attention. Scientists who warn that this catastrophe is unfolding assert that arthropods – a large category of invertebrates that includes insects – are rapidly declining, perhaps signaling a general collapse of ecosystems across the world.

The Texas frosted elfin (Callophrys irus hadros), a small butterfly subspecies found only in Arkansas, Texas, Oklahoma and Louisiana, has lost most of its prairie habitat and is thought to have dramatically declined over the last century. Matthew D. Moran, CC BY-ND

Matthew D. Moran, Hendrix College

Starting around the year 2000, and more frequently since 2017, researchers have documented large population declines among moths, beetles, bees, butterflies and many other insect types. If verified, this trend would be of serious concern, especially considering that insects are important animals in almost all terrestrial environments.

But in a newly published study that I co-authored with 11 colleagues, we reviewed over 5,000 sets of data on arthropods across North America, covering thousands of species and dozens of habitats over decades of time. We found, in essence, no change in population sizes.

These results don’t mean that insects are fine. Indeed, I believe there is good evidence that some species of insects are in decline and in danger of extinction. But our findings indicate that overall, the idea of large-scale insect declines remains an open question.

The debate

For most scientists, the idea of disappearing insects is a foreboding prospect that would have harmful repercussions for all aspects of life on Earth, including human well-being.

But some scholars were skeptical of the reported insect apocalypse. A number of studies that showed broad declines were limited geographically, focusing mainly on Europe. Typically these studies analyzed only a few species or groups of species.

Some particularly long-running assessments showed that declines in the past 30 years occurred after periods when the relevant insect populations increased. Many insect populations are known to naturally fluctuate, sometimes dramatically.

Many scientists concluded that while the prospect of mass insect losses was concerning, the jury was still out on what was actually happening. https://www.youtube.com/embed/bz4ODmqbnQA?wmode=transparent&start=0 Insects have evolved adaptations that enable them to live in a huge range of environments around the globe.

Spotlighting North America

Ecologist Bill Snyder and I thought that the studies suggesting widespread insect die-offs produced an intriguing pattern with important ramifications, but that the evidence wasn’t strong enough yet to draw conclusions. We wanted to examine what was happening in North America, which has an immensely diverse landscape and, surprisingly to us, had not been broadly analyzed for insect declines.

For our study, we decided to use data from sites in the Long Term Ecological Research network, which is supported by the National Science Foundation. The network includes 28 sites across the U.S. that have been studied in depth since the 1980s, and covers deserts, mountains, prairies and forests. With almost 40 years of data collected, we hoped trends at these sites would be a good complement to European insect studies.

Monarch butterfly caterpillar hanging from leaf
Monarch Butterfly (Danaus plexippus) larva preparing to pupate, or transform physically into a butterfly. This highly migratory species has declined across parts of its North American range in recent years. Matthew Moran, CC BY-ND

We put together a 12-person team that included six undergraduate students, post-doctoral scholars Michael Scott Crossley and Amanda Meier, and colleagues from the U.S. Department of Agriculture. When we finished compiling our data sets, at least some of us expected to see broad insect declines.

Instead, the results left us perplexed. Some species we considered declined, while others increased. But by far the most common result for a species at a particular site was no significant change. The vast majority of our species had stable numbers.

At first we thought we were missing something. We tried comparing different taxonomic groups, such as beetles and butterflies, and different types of feeding, such as herbivores and carnivores. We tried comparing urban, agricultural and relatively undisturbed areas. We tried comparing different habitats and different periods of time.

But the answer remained the same: no change. We had to conclude that at the sites we examined, there were no signs of an insect apocalypse and, in reality, no broad declines at all.

Three college students in field collecting insects with a large tube
Students from Matthew Moran’s laboratory at Hendrix College sampling insects in a natural prairie in Arkansas using a suction machine. Studies like these help scientist gather long-term data on insect populations. Matthew Moran, CC BY-ND

Explaining continental differences

We are confident in our analysis and our conclusion, but a more important question is why our results are so different from those of other recent studies. I see two potential explanations: location and publication bias.

As I have noted, most insect decline papers have come from European data. Indeed, Europe has better and more extensive long-term data than other parts of the world. It is also one of the most densely populated parts of the world – three times higher than North America.

Moreover, almost all of Europe’s land has been modified for human use. Agriculture is widespread and intense, and cities and suburban areas cover large swaths of the landscape. So perhaps it is unsurprising that Europe has also lost a larger proportion of its wild creatures compared to North America.

Publication bias is not about dishonesty or false results. It refers to the idea that more dramatic results are more publishable. Reviewers and journals are more likely to be interested in species that are disappearing than in species that show no change over time.

The result is that over time, declining species can become overrepresented in the literature. Then, when scholars go looking for papers on animal populations, declines are predominantly what they find.

We selected Long-Term Ecological Research sites for our analysis in part because they had “raw” data available that had not been peer reviewed for publication and were not collected in anticipation of finding declines. Rather, scientists amassed these data to monitor ecosystems and observe trends over time. In other words, it was unbiased data. And because the data sets were so varied, they covered a broad range of species and habitats.

The future of insects

Our study will not be the final answer. As the human population continues to grow and appropriates an ever larger share of the world’s land, water, space and biomass, other species can only retreat and survive with fewer resources. I have no doubt that every time a forest is cut, a prairie is plowed or a field is paved, the world loses some of its animal and plant life.

Quantifying this process will require more monitoring, more conservation biologists working in the field and more awareness of how human actions affect Earth’s biodiversity. But it may be possible that insects, who have survived for millions of years through a great many biological catastrophes, are finding a way to survive our presence too.

Matthew D. Moran, Professor of Biology, Hendrix College

This article is republished from The Conversation under a Creative Commons license. Read the original article.

43 thoughts on “Insect apocalypse? Not so fast, at least in North America

  1. 1953 on an August family vacation trip from Wisconsin to Yellow Stone my Dad’s 1950 Ford was covered in insects. He had the gas stations hose them out of the radiator. Lots of cars and us on the return trip had big screens on the front bumper to deal with them.

    2018 I made the same trip. Very few insects no need for a bug screen.

    When I moved into my current house in 1979 you couldn’t sit outside after sunset on a summer evening because of the mosquitoes. We still have them but not nearly like they were 40 years ago.

    A sample of one isn’t conclusive, but there is a reason people are questioning the insect populations

    • Cars use to eat insects because of their shape and lack of aerodynamics, now car typically just have the bugs fly over them with the air stream.
      i haven’t noticed any real change in the bug population from when I was a kid, though the lantern fly’s are all over the place, i kind of wish the insect apocalypse would target them.

      • Plus windshield wipers are frequently used during the last few decades to wash off the bugs.
        Back in the fifties, turning on the windshield wipers only spread bug goo across the windshield.
        So, drivers let the bug debris collect until they could be washed off at a gas station; remember, those were days of ‘full service’ which included washing windshields and even hubcaps.

        Rode with my parents from the East Coast to Los Angeles and back.
        I also drove my family across and back, twice.

        Most of the modern trips were mostly 4 to 6 lanes, minimum with significant land barriers on both sides.
        Back in the fifties, most of the highways were two lanes with private lands right up to the road’s shoulder.
        What difference? With fifty to a hundred yard roadway zones, there are fewer chances of disturbances sending clouds of grasshoppers, beetles, whatever into the roadway. Plus, back then there were far fewer cars on the road picking up bugs on the windshield.

        Back in the fifties, a car’s interior ventilation came from the engine compartment. I’ve been hit by a grasshopper and a bumble bee that managed to bounce through the ventwork. Nowadays, that air is typically filtered and often the air is picked up inside a fender.

        Mosquitoes? The biggest difference between when I moved into my house twenty six years ago and now is that I’ve searched out and eliminated a lot of standing puddles of water. Still plenty of mosquitoes to keep the martins and bats happy.

    • People drain swamps….just can’t stand them….over a period of 50 or 100 years this terraforming, wherever human population is growing and people are driving around, these major insect breeding grounds become significantly reduced, replaced by parking lots. In farming communities, insecticide use has ended grasshopper and caterpillar plagues. In forest campgrounds, they spray for mosquitoes so that urban visitors come back again. This explains your windshield and radiator observations. Also, those university Ph.D wannabes don’t normally drive very far off the beaten path to get their bug counts, or they would find insect populations are doing just fine in the backwoods, and there are so many bugs that reporting their demise is unnecessary.

      • “In farming communities, insecticide use has ended grasshopper and caterpillar plagues.” No not correct, the grasshoppers are dependent on dry weather damp weather causes a fungus that kills them. Army worms are also weather dependent. They are just as happy eating tree leaves as well as crops.

      • “DMacKenzie August 12, 2020 at 8:25 am
        People drain swamps….just can’t stand them….over a period of 50 or 100 years this terraforming…”

        No!
        It is illegal to drain swamps without extensive permitting obtained before draining.
        Most localities make it almost impossible to drain any sort of wetland without creating an equal amount of wetland elsewhere.
        This has been the case since the 1960s.

        I live on the edge of farming land. Grasshoppers, crickets, all kinds of caterpillars, potato bugs, lightning bugs, etc. are plentiful.

        People have been demanding farmers grow crops without using herbicides or insecticides.
        That worked for a few years but this year’s crops are noticeably damaged. Corn has cutworms, tomatoes and peppers are smaller, insect bitten and misshapen, fresh greens have aphids.

        Commercially it is impossible to manually clean crops of pests without massive amounts of manpower.
        Within a few years, farmers that want crops that sell will be using more insecticides. Ot they’ll charge substantially higher prices for their greatly reduced crops.

        But then, there are a lot of imported crops that claim “organic” but are not. They are grown in countries that have different regulations leaving the only problem is whether remaining chemicals are at testable levels.

    • Encouraging but like Steve above, I struggle to reconcile this with the “windshield test”. There are many fewer bugs on windshields now than in years past. The topic came up a few years back on a honey bee discussion board (what’s bad for other bugs is often bad for honey bees) and one of the participants did some serious wind tunnel tests. Contrary to Bob boder’s hypothesis, car aerodynamics did not play a significant part in bug deaths beyond a few models. (The Prius, for example, is actually optimized for aerodynamics but most other cars are just made to look fast. Trucks are basically still big bricks pushing their way through the air.) Something other than aerodynamics is at work.

      • What is the number of cars on the road now versus then?

        To use Steve Case’s example above from 1953 I think you’ll find the number dramatically different. Not being as old as I presume Steve is (no disrespect intended, I simply wasn’t alive in the 50s), my comparative experience would be the 1970s and while I’d agree that the “windshield test” is somewhat accurate, I’d also contend there were less than half as many cars on the road regularly in even the 1970s than we see now. I’d also suggest there are far more long-haul trucks on the road at this point as well.

        The logical (to me at least but then Occam did die some time ago) conclusion is that there are probably just as many insects out there but they are being killed by more vehicles rather than having time to cluster and be “consumed” by a single, occasional vehicle going through. Back in the 1970s we could go miles on I-94 between Fargo and Fergus Falls and not see a vehicle. Now I travel that route and I can’t go much more than a single mile without being passed, never mind what’s going by in the other direction.

        In that aforementioned stretch of road in North Dakota I have had to stop the car and physically scrape bug guts off the windshield to improve visibility because it was too think to see out. As recently as last year. But that’s just anecdotal, it was a cluster of aquatic midges over a long stretch owing to a rainy summer. But in my mind so much of the “windshield test” is also anecdotal.

        That’s not to suggest that there is zero impact on insect populations because there has been. It’s primarily due to habitat alteration. Agriculture has changed massively in response to population increase. The urban/suburban populations have spread out tremendously from what they were in the first half of the last century. It would be illogical to contend this hasn’t had substantial impacts. Microhabitats that were present for many specialized species have been completely paved over. But that’s all done. We can’t undo those habitat losses. I also seldom find volunteers to stop eating food.

      • Mike Rossander August 12, 2020 at 9:30 am
        …Contrary to Bob boder’s hypothesis, car aerodynamics did not play a significant part in bug deaths beyond a few models…

        Thanks, now I don’t have to be crude and answer Bob’s post with “Bullshit!”

    • Mosquito abatement is conducted in almost every community in the US. In many it’s another taxing district. That’s where the mosquitoes went.

    • Agree Steve C,
      I would describe this as a non-linear, perhaps even an exponential decline…
      I do not wish to pretend any insight; however, I would consider the great solar minimum + decline in Earth magnetic field => increase in surface reaching cosmic radiation to be a potential driver…

    • The number of insects your car hits on a trip depends not only on the month, but on a particular day and time of day.

      I live in Tokyo, which saw a rather late start of the summer season. Cool and rainy weather was persistent for the first 3 weeks of July. The result of this weather resulted in the late appearance of our summer cicadas. At a time of the month when the trees in the local cities park were normally covered with cicadas, and the noise was usually deafening, there were none to be seen or heard,

      But at the beginning of August, summer hit us in full strength, and the cicadas are so numerous that they are molting on top of each other after crawling up out of the ground. The ground at the nearby park is so full of holes that it looks like Swiss cheese. The noise is deafening, and my dog doesn’t want to walk near the trees.

      In the American South (I know it well, having served in the Army in Alabama and Georgia) the insects are seasonal. The love bug season is the worst, yet the season does not always start on the same day, or same week. You may drive through clouds of them in the 3rd week of August this year, or you may not.

      Tokyo does not have a lot of bugs compared to the Japanese countryside, but there is no lack. Summer in any part of the 40 million population metro are means mosquitos, cicadas, butterflies, “shield bugs” and whatnot. The one insect there are few of are houseflies.

  2. Do we worry about subspecies now? Not so long ago, every stream in California was populated by a separate local subspecies of trout …

  3. Last year and again this year in southwestern Massachusetts, we are seeing and photographing more than a dozen monarchs a day. We don’t recall ever seeing so many, now two years in a row. Last fall, we found difficult avoiding them puddling on dirt road.

  4. There is no shortage whatsover of all sorts of insects around our place in Victoria (yes, that one!) in Australia. From tiny little flies to massive rain moths and everything in between. We sweep up some of them in their thousands after they come into the house. 🙁

  5. The non-collapse result makes me wonder if this group will have trouble getting funded.

  6. Annecdotal… for what it’s worth. Here in New Hampshire I’ve noticed a significant decline in moths and mosquitoes at night over the last few years. I think the number of songbirds is down too, but I can’t verify any of these observations.

    • I spent considerable time going through real climate during the spring. They occasionally raise some interesting points but my ultimate conclusion was that if you don’t agree with them, 100%, you’re a denier. Or, I suppose, as you have pointed out, they are going for a new label – alternative scientists. I guess they’re trying for a Trump association with that.

      In reviewing their site in the spring I got a particular kick out of their section on PAL review, where they slam a number of articles for conspiracy. The basic premise being that like minded scientists allowed other like minded scientists to publish peer-reviewed but objectionable (to them) articles. I LOL’d. They threw shade on the whole climate-gate fiasco without even realizing it. I’m quite certain that they have no realization of it to this day. OK, Willie Soon and others do PAL review, but Mann et. al. don’t? Right.

    • The Real Climate site stated (in relation to the AFD which they were debunking):

      “Another sign that should make you skeptical is if the claims have a dogmatic character. The AFD address is all dogma. This is also typical among the science deniers.”

      Strange that just about every Climate Alarmist site I have come across has claims of a dogmatic character. Should that make me sceptical (correct English spelling)? And what could be more dogmatic than to call for so-called ‘climate deniers’ to be imprisoned?

      I don’t know if the use of Hydroxychloroquin + zinc is effective for treating mild to moderate cases of Covid19, nor do I know if the use of Ivermectin + Doxycyclone + zinc is effective for moderate cases of Covid 19. It seems that these treatments are recommended by TV stars – or rather they say that there should be no legal barrier against their use -as against the dogmatic opposition to their use on the grounds that some studies have been said to indicate that there was no benefit.

      • Please see the international study comparing the death rates of countries that used HCQ/AZ/zinc as opposed to those that did not! Those nations that used the HCQ cocktail early in the “pandemic” had 80% lower death rates than those that did not! Of course they were lead by powerhouse nations with world beating health care systems like Turkey, Morocco and Indonesia. The US and the UK look more like third world nations in comparison due to their politicization of a tried and true anti-viral drug! An article in Real Clear Politics describes this study as well as the findings in Switzerland that HCQ use was directly linked to lower death rates! The only reason to outlaw use of HCQ is that President Trump touted it as possibly effective against the virus and you hate him more than you value human life; or you stand to make a large amount of money off of a new vaccine whether it is as effective as the HCQ mix or not

  7. My truck has no problem collecting bugs. Anyone worried about bugs is welcome to come hay my fields. It’s like being in a bug tornado.

  8. “As the human population continues to grow and appropriates an ever larger share of the world’s land, water, space and biomass, other species can only retreat and survive with fewer resources. ”

    The premise of this statement may not be true. There is substantial reason to believe that we are close to the end of the modern growth phase of the human population.

    I cite below a new article from Lancet projecting low population growth on a global scale. The article projects the US population in 2100 to be 336 million, just barely larger than it is today (331 M) and that the peak US population will be 364 M in 2062.

    Also: “Empty Planet: The Shock of Global Population Decline” by Bricker and Ibbitson (2019) https://www.amazon.com/gp/product/1984823213/geneexpressio-20

    Good analysis of what it all means by Walter Russell Mead: “Snooze the Climate Alarms” | July 27, 2020 | https://www.wsj.com/articles/snooze-the-climate-alarms-11595889568

    “Fertility, mortality, migration, and population scenarios for 195 countries and territories from 2017 to 2100: a forecasting analysis for the Global Burden of Disease Study” | Vollset, Goren, et al. | July 14, 2020 | DOI:https://doi.org/10.1016/S0140-6736(20)30677-2

    https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)30677-2/fulltext

    * * *

    Methods: We modelled future population in reference and alternative scenarios as a function of fertility, migration, and mortality rates. We developed statistical models for completed cohort fertility at age 50 years (CCF50). Completed cohort fertility is much more stable over time than the period measure of the total fertility rate (TFR). …

    Findings: The global TFR in the reference scenario was forecasted to be 1·66 (95% UI 1·33–2·08) in 2100. In the reference scenario, the global population was projected to peak in 2064 at 9·73 billion (8·84–10·9) people and decline to 8·79 billion (6·83–11·8) in 2100. The reference projections for the five largest countries in 2100 were India (1·09 billion [0·72–1·71], Nigeria (791 million [594–1056]), China (732 million [456–1499]), the USA (336 million [248–456]), and Pakistan (248 million [151–427]). … 23 countries in the reference scenario, including Japan, Thailand, and Spain, were forecasted to have population declines greater than 50% from 2017 to 2100; China’s population was forecasted to decline by 48·0% (−6·1 to 68·4). China was forecasted to become the largest economy by 2035 but in the reference scenario, the USA was forecasted to once again become the largest economy in 2098. Our alternative scenarios suggest that meeting the Sustainable Development Goals targets for education and contraceptive met need would result in a global population of 6·29 billion (4·82–8·73) in 2100 and a population of 6·88 billion (5·27–9·51) when assuming 99th percentile rates of change in these drivers.

    Interpretation: Our findings suggest that continued trends in female educational attainment and access to contraception will hasten declines in fertility and slow population growth. …

    • It’s, I think well known, that the biodiversity in big cities like Berlin or Munich is often much higher than on country side with monocultures or intensive agriculture.

      Not to forget: German Wind Turbines Kill 1,200 Tons Of Insects Per Year (only Germany)

      Insects can halve wind-turbine power

      Insects can halve wind-turbine power

      For no apparent reason, the power of wind turbines operating in high winds, may drop,
      causing production losses of up to 25%1. Here we use a new flow visualisation technique to
      analyse airflow separation over the blades and find that insects caught on the leading edges in
      earlier low-wind periods are to blame. These potentially catastrophic power glitches can be
      prevented simply by cleaning the blades.

      • Beautiful. I will definitely use that. Green wind generators output substantially decreased by massive insect slaughter.

  9. Insect Apocalypse? There is writing called the Animal Apocalypse. It is a unit of the Book of Enoch, a sacred writing of the pre-christian era. It is canonical scripture only in Ethiopia:

    Book of Enoch–https://en.wikipedia.org/wiki/Book_of_Enoch

    The Animal Apocalypse, Part 1 – 1 Enoch 85-90–https://readingacts.com/2016/06/22/the-animal-apocalypse-part-1-1-enoch-85-90/

    The Animal Apocalypse, Part 2 – 1 Enoch 85-90–https://readingacts.com/2016/06/23/the-animal-apocalypse-part-2-1-enoch-85-90/

  10. Where I live, which is semi remote and off the beaten path (except for an international flight path) I would never know that there was anything out of the ordinary going on. There are just as many bugs, if not more, since the plants, grass and trees are growing much more rapidly. There are fewer mosquitoes this year, even though it is an extra wet season in the more northern parts of the Pacific North West. This is because it has been much colder than normal. In fact yesterday only got to about 49 degrees and last night, we had a frost at 3000 feet elevation. This is the earliest frost I have seen here in 41 years for August, although we did have snow once on Aug 19th, with an even deeper frost. This must be due to the La Nina that is building, and the Beaver are extra busy cutting down everything they can and building up their food supplies for winter.

    The one thing I have noticed, is that the Willows and Alder are growing like they are on steroids. I have historical pictures of a lot of my area, and the older 100-150 year old photos most definitely don’t show these broad leaf deciduous trees growing like this. I have to attribute this to the additional CO2, which is a godsend to the biosphere. Only one negative I see here is that the Barn Swallows all disappeared. Used to have hundreds of barn swallows in my barn, but now not a single one. I assume this local flock got wiped out somewhere else in their annual migration to Central and South America.

    • Our swallows moved away when a flock of crows moved into the adjacent belt of trees. As far as insects goes, there are plenty, but they won’t last long – last night the temperature went down to 10C.

    • Our swallows moved away when a flock of crows moved into the adjacent belt of trees. As far as insects goes, there are plenty, but they won’t last long – last night the temperature went down to 10C.

  11. Sometimes it’s only a difference between a cold or a mild winter. In Switzerland due to a relatively mild winter we have a wasp year… which means less flies (the wasps eat them)…

  12. I have a summer place in northern Michigan and have two boats. I have to clean the boats at least once a week to get rid of spiders and all the insects they trap. I would be happy if someone came up with a way to dramatically reduce the population of spiders. In similar vein, for those who claim they are not seeing as many insects on their vehicles windshields, I would appreciate it if you would come over and clean the bugs of my vehicles.

  13. If insects are declining, then won’t turning the rest of the planet into ecological deserts buy building solar/wind/biofuel green energy accelerate the whole process?

  14. While I picked a place to live that has few mosquitoes, fleas and ticks; I do wish the supposed Apocalypse would come for the Five-spotted Hawkmoth that brings me their Tomato Hornworm larvae! When I catch one of these plug uglies eating their way to the top of a tomato plant I pluck them off and do a little victory dance over them! Next year, though, I hope they will be suffering from the bT’s! Other than that we should never forget that trout think of grasshoppers like many people think of chocolate; even with a hook in them!

  15. Just yesterday there was an article about how climate change was going to make ticks go rampant.
    Now they are telling us that climate change is going to kill off all the insects.

    Can’t they make up their minds regarding just how climate change is going to kill us?

    BTW, I see a lot more bugs in summer than I do in winter, so I find it hard to believe that a degree or two of warming (not that it will anywhere near that much) is going to kill off the bugs.

Comments are closed.