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.
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.
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.
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