Most people are familiar with the story about the passenger pigeon. They were so numerous in the late 1800s that hundreds of millions of them dotted the sky for hours. In just over 100 years, humans exterminated them. The last wild passenger pigeon was shot in 1901. The Rocky Mountain locust is a similar story, though few people have heard of it. Once quite common, swarms would sometimes erupt from the eastern Rocky Mountains and spread eastward across the Great Plains. One particular large swarm of this grasshopper, estimated to contain 12.5 individuals, was discovered in 1875. TrillionIndividuals, the most common living organism known to man. It went extinct in 28 years, the last one being in 1902. It is not clear what caused this most extreme of extinctions. However, it appears that the locust’s main breeding ground was Montana and Wyoming where it laid its eggs in sandy soils. These areas were fertile and easy to cultivate, so they were among the first to be settled by farmers and plowed, destroying the eggs of locusts.
A wider bias is evident in the contrast between public awareness and the fate of the Rocky Mountain locust and the passenger pigeon. We tend to be more concerned with large animals, especially birds and mammals, and less about the smaller creatures that are insects and their kin. Children are often fascinated with insects, but unfortunately they grow out of it. Teenagers and adults tend to try to swat or stamp on any insect that is near them. Even the common names we give insects, such as “bugs” and “creepy-crawlies,” reflect this negative attitude.
I fell in love early on, at just five or six years old. My childhood obsession with insects never left me and I’ve been able to make a career of studying their fascinating lives. My mission is to inspire others to respect and care for insects. We all need them, regardless of whether we realize it or not. The world’s 1.1 million insect species account for more than two-thirds (23%) of all species. About three-quarters (or more) of the crops we plant, including most of our fruits and vegetables, are pollinated or controlled by insects. Many of us would be starving if they didn’t exist. They also pollinate most wildflowers, recycle dung, leaves, and corpses, and help to keep the soil healthy and pest-free. They provide food for many larger animals like birds, frogs, and even lizards. Without insects, ecosystems would come to a grinding halt.
We should all be concerned that insects are declining. Every year there are slightly fewer butterflies, fewer bumblebees — fewer of almost all the myriad little beasts that make the world go round. While estimates can vary and are uncertain, there is a trend of declining numbers in many insects, particularly those found in the tropics. The data we have however strongly suggest that this trend is occurring. In Germany, for example, the biomass of flying insects has fallen by 76 percent over the 27 years from 1996 to 2016. The U.S. monarch butterfly population has declined by 80 percent in the last 25 years. The U.K. has seen a halving of the number of butterflies since 1976, when I was just 11 years old. These changes have been occurring in our lifetimes and continue to accelerate.
My youngest son, now 11, is now 11. He is now growing up in an age where butterflies are half as common than when I was his age. What number of butterflies will his children see?
Paul Ehrlich, a famous American biologist, compared the loss of species in an ecological community to randomly popping rivets off a plane’s wing. The plane will likely be fine if you only remove one or two. You can take out 10, 20, or 50 and the plane will likely be fine. However, at some point that we are unable to predict, the plane will crash from the sky. Insects are, in his words, the rivets that hold ecosystems apart.
What is driving the decline in insects? There are many factors that can contribute to the decline of insects. However, the industrialization and dependence on pesticides, especially large-scale monoculture crops, is clearly a major factor. Rachel Carson warned us in her book “The Year 1962”, three years before my birth. Silent Spring We were doing terrible harm to our planet. She would weep at how much it had gotten worse. Carson was very clear that pesticides and fertilizers have been causing more problems than ever before. Some of these new pesticides, such as neonicotinoids, are thousands of times more toxic to insects than any that existed in Carson’s day. Particularly, the U.S. has a gung-ho approach to pesticides. U.S. farms are particularly affected. accounting for nearly 20 percent of all global use. Due to concerns about risks to human and environmental health, around one quarter of pesticides currently used in the United States are now banned by the European Union. The United States allows pesticides that are banned in China or Brazil. Neither country is known for its sensitive approach towards environmental protection.
The Rocky Mountain locust may have been extinct, but other grasshoppers still exist in the same region, and occasionally, there are outbreaks that spread to neighboring states. The grasshoppers eat grass, which can impact ranchers and livestock. One such outbreak occurred in summer 2021. In response, the federal government funded aerial spraying on approximately 1,000,000 acres of rangeland across Montana and neighboring states with diflubenzuron. The decision makers claim that the chemical is harmless to other insects. However, this is nonsense as the chemical is used commercially to kill many moths, flies, termites and beetles. highly toxic to bumblebees. The chemical is toxic to many plants. What is the collateral damage to the landscape from carpet-bombing? Montana is home to thousands of native insects. This spraying will result in the death of trillions of individual insects, including monarch butterfly caterpillars. This will impact the functions of these insects; fewer pollinators for crops or wildflowers means fewer insects that birds can eat. Chicks of many birds, such as the endangered greater Sage grouse, can rely on grasshoppers for protein. The birds, in turn, help to keep grasshoppers under control. The birds and other natural enemies of the grasshoppers could be further decimated, which would lead to more insecticide being sprayed. It is a self defeating war on nature that will never be won. I find myself wondering if the crop duster pilots play “Ride of the Valkyries” on their cockpit radio, while muttering “I love the smell of insecticide in the morning.”
Pesticides aren’t the only problem that insects face in today’s world. Ongoing habitat loss — particularly of tropical forests — and the spread of invasive species and non-native insect diseases are all taking their toll. Light pollution is a major problem for night-flying insects. It attracts many insects that are attracted to artificial lights and makes it difficult for them to determine the length of the day and when they should emerge from hibernation. Many soils are in danger of being degraded and rivers polluted by chemicals or so much water that they run dry. Climate change, a phenomenon unrecognized in Rachel Carson’s time, is now threatening to further ravage our planet. The failure of COP26 in achieving any meaningful international progress on climate change means that insects will need to be able to withstand more frequent droughts and wildfires, floods, and storms in the future. It is death by a thousand cuts.
Our planet has remarkably survived the blizzards that have been wrought on it, but we are foolish to believe that it will continue to cope. Although a small number of species have gone extinct, almost all wild species are now in a fraction of their former numbers, living in fragmented and degraded habitats, and being subject to a variety of man-made challenges. We don’t know enough to predict how resilient our ecosystems will be, or how close we are from the tipping point beyond which collapse is inevitable. In Paul Ehrlich’s “rivets on a plane” analogy, we may be close to the point where the wing falls off.
Learn more about insect declines, and what you can do in order to reverse them. Silent Earth Published by Dave Goulson HarperCollins 2021