Insect Demise

The first creatures to evolve on land, insects have a crucial presence on Earth. Their passing presages our own doom.

Insects are not only a critical food source for numerous vertebrates, they also serve as essential pollinators to flowering plants, including many crops which feed humanity.

Deforestation and other disturbances have decimated insect populations worldwide in the past century. “The main cause of the decline is agricultural intensification,” said ecologist Francisco Sánchez-Bayo. “That means the elimination of all trees and shrubs that normally surround the fields, so there are plain, bare fields that are treated with synthetic fertilisers and pesticides.”

There has been a synchronous decline in the amphibians, reptiles, birds, and bats that eat arthropods. “It’s death by a thousand cuts,” lamented ecologist David Wagner.

Among the thousand cuts is heat. As ectotherms, insects rely upon a limited temperature range to live. Overheating threatens both insect reproductivity and their very survival. Global warming is happening faster than can be met by adaptation. “If we don’t stop it, entire ecosystems will collapse due to starvation,” Sánchez-Bayo concludes.

The mass die-off of insects at the present rate is unprecedented in geological history. The mass extinction that did in the dinosaurs 66 million years did not dent insects nearly as grievously as now. Insects got past the Great Dying – the worst mass extinction on Earth – better than presently.


Jeremy Hance, “One year on: Insects still in peril as world struggles with global pandemic,” Mongabay (11 November 2020).

High temperatures threaten the survival of insects,” ScienceDaily (10 November 2020).

FranciscoSánchez-Bayo & Kris A.G. Wyckhuys, “Worldwide decline of the entomofauna: A review of its drivers,” Biological Conservation (April 2019).

Erik I. Svensson et al, “Selection on phenotypic plasticity favors thermal canalization,” PNAS (9 November 2020).

Elizabeth Kolbert, “Where have all the insects gone?,” National Geographic (23 April 2020).

Douglas Main, “Why insect populations are plummeting – and why it matters,” National Geographic (14 February 2019).

Bradford C. Lister & Andres Garcia, “Climate-driven declines in arthropod abundance restructure a rainforest food web,” PNAS (15 October 2018).

Eero J. Vesterinen et al, “A global class reunion with multiple groups feasting on the declining insect smorgasbord,” Scientific Reports (6 October 2020).

Dietary overlap of birds, bats and dragonflies disadvantageous in insect decline,” (10 November 2020).

Damian Carrington, “Plummeting insect numbers ‘threaten collapse of nature’,” The Guardian (10 February 2019).

Caspar A. Hallmann et al, “More than 75 percent decline over 27 years in total flying insect biomass in protected areas,” PLOS One (18 October 2017).