New global insect species estimates reveal 13.3 to 24.7 million species, prompting biodiversity rethink

Summary

The Conversation reports a major shift in how we count Earth’s insects, suggesting there are likely between 13.3 million and 24.7 million species, with a conservative average of about 20.3 million. This significantly exceeds traditional figures and reinforces the idea that biodiversity is far richer than previously thought. The study is careful to describe the number as a lower-bound estimate, meaning there could be many more species awaiting discovery. The work also connects insect diversity to essential ecosystem services such as pollination, pest control, soil health, and waste decomposition, and it situates its findings in the context of biodiversity extinction concerns raised by IPBES. The article is published by The Conversation.

• Insect diversity may be far higher than previously believed.
• New methods adapt epidemiology statistics to biodiversity counts.
• A Costa Rica case study reveals earlier surveys captured only a fraction of species.
• Counts have implications for ecosystem services and extinction risk assessments.

Overview

The article examines a new study that revises the global count of insect species upward, arguing that the planet likely hosts between 13.3 million and 24.7 million insect species, with a conservative average near 20.3 million. This challenges long-held estimates that ranged from five to six million and even the widely cited eight to nine million figure from earlier work. By reframing the problem and using methods borrowed from statistical epidemiology, the authors aim to provide a more credible picture of terrestrial biodiversity and the unknowns that still persist in this vast, diverse group.

Estimating the incompletely observed world

The piece begins by placing insects at the center of ecosystems, highlighting their roles in pollination, pest control, soil aeration and waste decomposition. It then explains why counting insect diversity is so difficult: their vast diversity, small size, and often hard-to-reach habitats make comprehensive surveys impractical. Despite progress—about 1.9 million described species since Linnaeus—the total number of insect species on Earth remains uncertain. The new study uses a lower-bound framework to avoid overstating precision in a field characterized by incomplete data and uneven sampling across taxa and regions. This cautious approach acknowledges that undiscovered species are abundant, particularly among small, cryptic or understudied groups.

Learning from parasitic wasps

To improve estimation, the researchers borrowed techniques from statistical epidemiology, applying them to a selected group of parasitic wasps, Microgastrinae, in the Área de Conservación Guanacaste in Costa Rica. They compared results from multiple collecting methods, each tallying only a fraction of the total species, and found that earlier studies captured only about 16 percent of the total Microgastrinae wasps present in the park. By extrapolating this fraction to all known insect species in the park and then scaling to Earth-wide patterns using established park-to-Earth ratios for various organisms, the authors derived the global insect species range. The result is a strikingly higher estimate than conventional wisdom, with the conservative mean around 20.3 million.

Broader implications for biodiversity and extinction

The article emphasizes that the new insect count would double the number of species considered threatened with extinction when compared to prior assumptions (IPBES had warned that about one million species were at risk, assuming Earth hosted eight million species). This has practical implications for conservation policy and for understanding the resilience and functioning of ecosystems. The authors stress that biodiversity loss is not just an environmental concern but also an economic and social issue, given insects’ foundational ecological roles and services.

Unknowns and a call for better data

Beyond the headline numbers, the piece underscores a critical point: the true extent of Earth's insect diversity is far from settled. The estimated lower bound signals that millions more species may still be undiscovered, and many could remain enigmatic to science even as they disappear. The article closes with a warning: if current biodiversity declines accelerate, we may lose crucial lineage, interactions and ecosystem processes before we even know they existed. The Conversation frames these findings as a reminder that counting diversity is a necessary precursor to protecting it, and that better data and methods are essential for effective conservation planning.