What are insects and why do we need them?
Insects are defined by six legs, three body segments — head, thorax, and abdomen — two antennae, and typically one or two pairs of wings. They include bees, ants, butterflies, grasshoppers, beetles, and countless other groups, and they make up more than 80% of terrestrial species on Earth. Their diversity and abundance make them essential to the health and function of ecosystems worldwide.
Insects support the production of many seeds, fruits, and vegetables through pollination and play a vital role in decomposing organic matter. They also provide a range of other ecosystem services that are critical in agricultural, natural, and urban environments. Many insect species help regulate pest populations through biological control, while others serve as bioindicators of healthy streams, soils, and landscapes. Together, insects form the foundation of complex food webs and contribute to the resilience, productivity, and ecological richness of the environments people depend on every day.
At the same time, some insects can cause serious harm. Certain species are major pests of crops, landscapes, and urban areas. Others spread diseases that threaten human, animal, and plant health. Invasive insect species can damage crops, disrupt ecosystems, and create far-reaching consequences for biodiversity, food security, and livelihoods. Insect-borne diseases also contribute to millions of human deaths each year.
As globalization accelerates and climates continue to change, the abundance, diversity, and distribution of insect communities are also shifting. Understanding where insects live, how they respond to environmental change, and what drives their population trends is essential for sustaining healthy ecosystems, supporting beneficial insects, and reducing the impacts of harmful species.
Evidence of Global Insect Declines
The evidence for global insect declines is substantial. Scientists and environmental researchers have documented insect population losses for decades, with concern about these trends dating back to the early twentieth century.[1, 2] In 2017, a long-term study reported declines of more than 75% in insect biomass in protected areas in Germany,[3] helping bring international attention to the issue and prompting broader discussion about the scale and causes of insect losses worldwide.[4, 5]
Although researchers continue to debate the interpretation of individual studies,[5] the larger pattern is clear: many insect populations are declining across regions and habitats. These declines have been observed not only in heavily developed areas,[6, 7] but also in remote environments with limited direct human disturbance, including the Arctic.[8] Taken together, the available evidence underscores the need for continued research, conservation, and action to help halt and reverse insect declines.[9]
What Is Driving Insect Declines?
The factors contributing to insect declines are similar to those affecting biodiversity more broadly.[10] Habitat loss and fragmentation remain among the most significant pressures.[11] Other major drivers include pollution from artificial light, microplastics, and synthetic pesticides;[12, 13, 14] the spread of pathogens and parasites;[15] and climate change.[16, 17]
In many cases, these stressors do not act alone. Instead, they interact in ways that can intensify pressure on insect populations and accelerate biodiversity loss.[10] Understanding how these factors work together is important for designing effective conservation strategies and management responses.
What Would a World Without Insects Look Like?
The services insects provide have an estimated annual economic value of US$57 billionUS$57 billion.[18] More importantly, their ecological value is foundational. Insect pollinators such as bees, flower flies, and butterflies pollinate more than 85% of wild flowering plants[19] and more than 75% of agricultural crop species.[20] Without these pollinators, food systems and natural plant communities would be dramatically altered.
The loss of part or all of an insect community can disrupt food webs[21, 22] and reduce the ability of ecosystems to recover after disturbance.[23] Some dragonfly species help control mosquitoes that can spread disease,[24] while lacewings can suppress agricultural pests such as aphids and mites.[25] Beetles also play an important role in removing waste from the environment,[26] and dung beetles introduced on farms have been shown to support disease resistance related to foodborne pathogens.[27]
In short, insects are not only abundant — they are indispensable. Protecting insect biodiversity helps protect ecosystem function, agricultural productivity, environmental quality, and human well-being.