Climate-Change Impact on Insects 'Simply Cannot be Ignored'

beetles in Luquillo Forest, Puerto Rico

By Michael Parrella, Ph.D.

A study published October 15 in the Proceedings of the National Academy of Sciences convincingly documents remarkable declines in tropical arthropod abundance in Puerto Rico due to climate change over the past four decades. (Also see “‘Hyperalarming’ study shows massive insect loss,” by The Washington Post’s Ben Guarino.) This comes on the heels of the most recent report from the Intergovernmental Panel on Climate Change, which warns that, if we do not act now to reduce the rate of climate change, we risk permanently changing Earth’s environment and most life adapted to live in it.

The evidence from this and other studies documents sharp insect declines and is increasingly clear: Climate change has claimed many insect victims. While some might wonder why fewer insects is a bad thing, it’s crucial to remember that insects are a key component of food webs. The study in Puerto Rico drives this point home, as it also found declines in frogs, lizards, and birds that eat insects. All life is inextricably linked through such food webs. Animals we consider essential to our existence depend on insects, directly or indirectly, for their own existence, as well—so we depend on insects, too.

Why else should Americans care about climate change and the decline of insect biodiversity? After all, doesn't this mean there will be fewer insects that bite and bother us? Not necessarily: These bothersome insects may have been kept in check by beneficial insects that are less able to cope with a changing climate. And pest insects may also follow the climate they prefer and become established in new places, bringing along their negative impacts on crops, human and animal health, and biodiversity. Meanwhile, we also face the loss of species critical to our food security, such as crop pollinators.

And so climate change is not just a concern for our kids or future generations. It is happening now at an alarming rate as repeatedly demonstrated by careful studies involving a wide range of disciplines within the biological and physical sciences. Yet, global climate change in public discourse is often replaced by political bickering. The urgency of these findings is diminished when our attention wanders from the big picture by arguing over minutiae or focusing on what the impacts will be decades from now. The reality is that we currently face emerging catastrophes in real time that simply cannot be ignored. Rapid climate change destabilizes the conditions necessary for long-term environmental and economic security. These recent studies showing the loss of insects are yet another canary in the coal mine indicating we are losing this stability, and it will ultimately cost us in ways we don’t fully understand. 

Within the entomological field are scores of scientists who study how climate change has affected insect biodiversity and how this in turn affects our lives by eroding food security, escalating vector-borne diseases, and opening the door to invasive species around the planet. We are worried about what the data are telling us, we are worried about the lack of conversation about the immediate effects of climate change, and we are worried about the lack of solutions being implemented to counteract climate change before it is too late—both for insects and for all the other organisms, including humans, that rely on them. When this many insects appear to be dying across the globe, it should worry us all.

Michael Parrella, Ph.D., is president of the Entomological Society of America and dean of the College of Agricultural and Life Sciences at the University of Idaho.

ABOUT: ESA is the largest organization in the world serving the professional and scientific needs of entomologists and people in related disciplines. Founded in 1889, ESA today has nearly 7,000 members affiliated with educational institutions, health agencies, private industry, and government. Headquartered in Annapolis, Maryland, the Society stands ready as a non-partisan scientific and educational resource for all insect-related topics. For more information, visit

Photo: Iridescent beetles near summits of East Peak, Luquillo Experimental Forest, Puerto Rico, where the study "Climate-driven declines in arthropod abundance restructure a rainforest food web," by Bradford C. Lister and Andres Garcia, published October 15 in Proceedings of the National Academy of Sciences, was conducted. (Photo credit: Flickr/US Forest Service Southern Region, CC BY-SA 2.0)