Elsewhere in the United States, some studies have reported stark declines in insects, while others have not. Thus, both the magnitude and causes of the insect die-off in this country are murky. Yet we need to pay close attention to what’s going on. Any widespread, large drop in insect abundance could have lasting, severe consequences on a par with other, better-known environmental threats.
Unfortunately, we don’t monitor insect populations in the United States with any vigor or consistency, apart from butterflies and some agricultural pests. But insects, like all species, suffer when their habitats are plowed or paved over. They are also fatally drawn to lights and vulnerable to pesticides, ranging from the ones we pour on croplands by the ton to the ones we use on lawns and gardens. These pesticides include chemicals designed to kill insects (insecticides) as well as those designed to kill weeds (herbicides). And what is a weed to a farmer or a gardener is an important food plant for some beneficial insects. The total amount of pesticides applied to U.S. crops has declined in recent years, but their toxicity to insects and weeds has increased greatly, likely resulting in more harm to insect populations. Unfortunately, no one knows the precise degree of harm caused by pesticides or any of the other threats, much less how these threats might interact with each to affect insect populations.
This shouldn’t be of concern only to insect aficionados. While some insects eat our crops or spread disease, the lives of humans and almost every other species on this planet are nonetheless dependent upon insects, whose roles as pollinators, decomposers and food for myriad other animals, including many birds and fish, are irreplaceable.
Indeed, a team of scientists based at the Cornell Laboratory of Ornithology published a report in 2019 announcing that the United States has lost 3 billion birds, equivalent to nearly 30 percent of the estimated North American total in 1970. Declines were noted in all regions of the country. The two of us have spent decades studying this long-term decline in bird populations. Our work and that of many other scientists has shown how the fragmentation of our forests due to development and the intensification of farming in grasslands has harmed birds. We now wonder whether we overlooked another major culprit: the decline of the insects they eat.
Over the years, the federal government has launched missions to the moon, to Mars and to the depths of the ocean. We now see an opportunity — an imperative, really — for the Biden administration to launch what we’ll call a mission to our own backyards: a scientific initiative to figure out what is happening to the insects (and the songbirds) — and, most importantly, what we can do about it.
The United States needs a nationwide network of sites in natural ecosystems, farmlands and gardens where populations of insects are monitored annually, akin to the North American Breeding Bird Survey, which is organized by the Interior Department, or the butterfly counts run by the Xerces Society and other organizations. For some insect groups — such as butterflies and dragonflies — there may already be enough amateur experts to do the monitoring at no cost. But given the tens of thousands of other types of insects in this country, we will need to hire and train more entomologists.
The mission should also include an expanded research initiative involving federal and state governments and universities to understand how the various threats to insects and birds interact with each other and what steps can be taken to reduce their impact. We can’t afford to wait another 17 years, until the offspring of this summer’s cicadas emerge, to get some clear answers.