Why the climate crisis is making our insects run for the hills (2023)

In the Alps and Apennines of southern Europe, nearly all the longhorn beetles are moving uphill, and way up at the peaks, the isolation of a brown butterfly with orange-tipped wings is pushing it towards extinction. This is a snapshot of a global trend. With temperatures rising and pressure on biodiversity growing, insects vital to our ecosystems are not only moving north and south, but up.

Research shows many animals are making similar moves, but insects’ high levels of mobility and short generation times allow them to respond quickly to change, meaning the uphill momentum can be rapid. Bumblebees in the Pyrenees have moved upwards on average by more than a metre a year, with some species making significantly greater journeys. Moths on Borneo’s Mount Kinabalu have followed suit.

All of this makes them a useful indicator of the speed of global heating and ecological impacts at higher altitudes – often biodiversity hotspots and havens for endemic species. To try to grasp the implications, scientists are filling their backpacks and lacing up their walking boots.

“If you want to track climate change on a mountain, you go a few metres. To do that with latitude, but on a flat basis, you have to move many kilometres,” says Prof Jane Hill from York University, who has spent years studying insects at elevation in the UK and the tropics.

Why the climate crisis is making our insects run for the hills (1)

While the broader altitude shift is disquieting in itself, studies have also shown that reproduction and development can be hit as insects move upwards. Other possible effects are simply unknown. What is undoubtedly true is that they are not uniformly distributed, and in general, the greatest existential threat does not face those making initial forays up from the lowlands.

For species long adapted to the cooler air of higher slopes, there are fixed limits to how far they can move to find conditions conducive to survival. And yet well over half of the mountain-dwelling insects that have been studied are shifting upwards.

An upland insect close to Hill’s heart is the mountain ringlet (Erebia epiphron), a priority species in the UK biodiversity action plan. After colonising the UK following the last ice age, this dark brown butterfly with orange “eyespots” on its wings has retreated northwards and upwards to the point it now only exists at high altitudes in Scotland and the Lake District. This isolation has made the populations genetically distinct.

“It’s not a butterfly you work on if you don’t like climbing a lot of mountains,” says Hill. “But the outcome is fabulous because you’re up on the tops of these hills with beautiful clear views, because of course the butterflies only fly when the weather’s pretty good.”

Without a reversal of prevailing trends or some creative intervention, such scenes are likely to become ever rarer. “The work we’ve done comes from the perspective of conserving their unique genetic diversity. Projections for climate change suggest that at the end of the next few decades, populations will disappear and we’ll potentially lose that,” she says.

The mountain ringlet is not the only threatened Erebia butterfly. The likes of the Scotch argus (Erebia aethiops), also in Britain, and the dewy ringlet (Erebia pandrose) in Italy and elsewhere are also feeling the thermal and genetic squeeze. Local extinctions of these specialists have long been occurring, with global heating a significant cause. Whether this leads to a more general disappearance rests on what happens now.

In ecology, finding the “smoking gun” to neatly explain any phenomenon is generally elusive, and so it is here. Uphill movements are associated with factors beyond climate; the package of “stressors” synonymous with the so-called “insect apocalypse”. For Dr David Roy of the Centre for Ecology and Hydrology, the UK illustrates this well.

“If you think about upland species in England, they would typically be hanging on in habitats like heathland or wetland. These habitats are being built on for houses, or they’re being farmed, or they’re being made more intensive. So a lot of those sorts of species are being lost anyway, regardless of climate. But I think the evidence is that climate is adding to that pressure.”

Loss of ice and snow is synonymous with global heating, and its impact can be felt by upland insects that both develop on land and in water.

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There have been some dire habitat loss predictions for aquatic insects at elevation because of glaciers melting, which affects the temperature and flow of rivers and streams. With these species tending to spend the vast majority of their lives in water as juveniles, it’s hardly a surprise that 51% of high-altitude freshwater species are now classed as “highly vulnerable”.

For terrestrial mountain species, snow cover can act as a buffer against extremes. If it melts, there’s a chance that things will get much more difficult for those whose development relies on snow as an insulating “blanket” to protect them at their most fragile.

“One thing that people don’t think about as much is context: how the environment or the climate has different effects at the egg stage or the larval stages of insects,” says Prof Christy McCain, who runs Colorado University’s Mountain Lab. “We tend to always measure the adults and in summer, but that might not be the most critical time for effects of climate change, and particularly on mountains where it gets incredibly cold and dry.”

McCain believes that the way data has been collected historically is hampering their understanding, with a glut of museum specimens from low elevations, and far fewer from higher up. And while numerous studies have looked at butterflies and moths, many other groups have been neglected.

“There’s definitely a bias towards certain charismatic species. The rest of the insects, they’re just so diverse and we know so little about them,” she says.

To illustrate her point, she refers to research on carrion beetles by a student at her lab. It has shown that climate tolerance may well be an inherited characteristic in this vital group of insects, which have a major hand in decomposition and live in microhabitats that could provide some protection against the extremes. The simple fact that insects such as these have been around since the Cretaceous, living through incredible climate changes, may also favour adaptation now.

There is no such thing as a “standard insect” or response to environmental change. For some groups, it might be a case of the bigger and more mobile they are, the better their chances. There is also no generic upland habitat – and this too could prove a saving grace.

Microclimates can have a disproportionate effect at higher altitudes, with landscape features resulting in cooler and warmer patches. In some locations, climatic effects may be somewhat cushioned, allowing the most exposed species to hang on.

“In areas such as the Pyrenees, there’s quite widespread abandonment of traditional farming in montane habitats, essentially because it’s hard work. Young people are moving out into the cities, and the older generation who used to farm these places are either not here any longer or have given up,” says Roy.

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“Some of those habitats are actually becoming more wooded, and this may be having the effect of cooling those environments at the same time as the climate is warming, and that might buffer against the loss of some of these species.”

Because of their enormous biomass contribution to ecosystems, changes in range and behaviour in social insects such as ants, termites and bees are an area ripe for study, says Dr Tom Rhys Bishop from Cardiff University.

His work is serving to underline the nuance at the heart of discussions around climate, habitat loss and biodiversity. In the tropics, ground-nesting ant species seem to be less at risk from rising temperatures than those that nest in tree canopies or leaf litter, quite simply because in response to the change, they can simply dig their nests deeper. Ants have shown an ability to adapt to both warm and cold conditions.

The huge impact of ant colonies on ecosystems could neatly serve to shed light on another important consideration: just what impact new arrivals at higher elevations have on those already there.

As things stand, the picture is not clearcut. In the Appalachian mountains, Aphaenogaster rudis, a traditionally low-elevation ant species, is displacing the closely related but cold-adapted species Aphaenogaster picea as it shifts upwards. In South Africa, a focus area for Bishop, similar phenomena have yet to be seen. There remain vast unknowns about such interactions, as well as much more fundamental matters.

“With climate change, things are going to get on average hotter, but also drier. That’s a major stress. But we have very little information on how lots of organisms respond to desiccation and aridity. So I’d say more information on physiological tolerances and performances is key,” says Bishop.

For social insects such as ants, bees and termites, a full understanding of the state of play across any range shift is all about the numbers.

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“It’s hard to find out, for example, how many new ant queens initiated colonies. That’s quite a different, practical problem to saying how many new elephant calves were born this year in Kruger National Park, where we can see all the elephants, tag them and follow them,” he says. “Getting a handle on these population level questions is really important for understanding climate change responses, yet we are almost completely blind within ants and all other social insects as to what those patterns might be.”

Tracking ants isn’t the only logistical problem faced by those collecting the data to fill considerable knowledge gaps. The mere fact that mountains can be remote and difficult to access is a fundamental barrier, albeit one that could be overcome with a mix of “citizen science” data from those visiting mountainous regions, and automated approaches.

“We’ve sort of gone from saying, ‘Insects have shown us some really important things about how humans are altering the landscapes’, to now thinking, ‘Right, now that they are shifting and showing these changes, and that climate change is being detrimental for many species, how can we go about thinking about how to conserve them?’” says Hill.

One of the more radical proposals is to assist genetically isolated species at the limits of their range in finding suitable homes. This might mean introducing species to unoccupied areas of suitable climate to preserve their DNA, or else moving them to areas with existing populations, which could improve genetic diversity as well as their capacity to adapt to further change.

While the underlying logic of such a plan seems sound, the idea of humans moving insects from one place to another tends to raise concerns that such intervention will have unintended effects on ecosystems. Hill is undeterred.

“I think we could bring together those with knowledge of how you can successfully do it, then draw up good guidelines,” she says.

Assuming the risks are judged to be low, it would then be a question of what appetite conservation organisations have for investing in the idea. It’s relatively easy to garner support for projects protecting the habitats of easily recognisable insects that provide clear benefits such as pollination in the lowlands. For that biodiversity which is “out of sight, out of mind” for many, a stronger case may have to be made.


Why are insects affected by climate change? ›

One way that insects cope with climate change is by shifting their range, or permanently relocating to places with lower temperatures. According to one study cited by Espíndola and other scientists, the ranges of nearly half of all insect species will diminish by 50% or more if the planet heats up 3.2°C.

How can climate change cause insect populations to grow? ›

Rising temperatures

An increase in temperature increases physiological activity and, therefore, metabolic rates. Insects must eat more to survive and it's expected that insect herbivores will consume more and grow faster. This will lead to increases in the population growth rate of certain insects.

Are insect populations declining due to climate change? ›

In fact, insects account for 80% of animal life on Earth. But, both the number and diversity of insects are declining around the globe due to habitat loss, pollution and climate change. Without widespread action, many of these important creatures face extinction within the next few decades.

Why do you think there is an increase in pest insects population when the temperature is increased in the environment? ›

The link with metabolism is straightforward. “When the temperature increases, the insects' metabolism increases so they have to eat more,” said Merrill, a researcher in UVM's Dept. of Plant and Soil Science and Gund Institute for Environment.

How does weather affect insects? ›

With the exception of the tropics, insect reproductive rates typically increase in warmer months, which is why you see more bugs when the temperature rises. As temperatures increase, so do the metabolic rates of insects, which means they need to eat more to survive.

How are insects affected by temperature? ›

Insects are cold blooded, and their metabolism and activity is very greatly influenced by the temperature of their bodies, which temperature is almost entirely dependent on that of the surrounding environment. A low temperature inhibits activity, and a higher temperature usually stimulates the animal.

How does climate change increase pests and diseases? ›

Ongoing increases in temperature and changes in precipitation patterns will induce new conditions that will affect insect populations, incidence of pathogens, and the geographic distribution of insects, weeds and diseases.

Why is climate change a threat to population of organisms? ›

As the climate changes, some species will adapt by changing their behavior, physical characteristics, or how their bodies function. Others will not be able to adapt. As a result, climate change could lead to expansions, reductions, or extinctions of some populations.

What happens to insect development in cold climates? ›

Insects that are inactive during the winter months undergo a state in which their growth, development, and activities are suspended temporarily, with a metabolic rate that is high enough to keep them alive. This dormant condition is termed diapause.

Does climate change increase insect borne diseases? ›

One way climate change might affect human health is by increasing the risk of vector-borne diseases. A vector is any organism – such as fleas, ticks, or mosquitoes – that can transmit a pathogen, or infectious agent, from one host to another.

What affects insect population? ›

Habitat loss, pesticides and climate change are threatening insect populations worldwide.

Does climate change cause insect borne diseases? ›

Rising temperatures favor agricultural pests, diseases and disease vectors (1). Therefore, climate change has already made conditions more conducive to the spread of certain infectious diseases, including Lyme disease, water-borne diseases, and mosquito-borne diseases such as malaria and dengue fever (2, 3).

What are the different effects of climate change on the population dynamics of insects? ›

The general consequences of global warming on insect dynamics include: expansion of geographic range, increased survival rates of overwintering populations, increased risk of introduction of invasive insect species, increased incidence of insect-transmitted plant diseases due to range expansion and rapid reproduction ...

Do insects struggle to adjust to extreme temperatures making them vulnerable to climate change? ›

Meta-analysis compiling data from over 100 insect species reveals weak ability to adjust thermal limits to high temperatures, making insects more susceptible to global warming than previously thought.

What temperature are insects most active? ›

Most bugs are more active in the warmer months of the year. When the temperatures are below 32 degrees Fahrenheit, insects really are not able to move. At 45 degrees, they start to move slowly. Insects don't become fully functional until temperatures reach 70 degrees.

Where do insects go during a storm? ›

Hiding in protected places such as under leaves, leaf litter on the ground, under rocks or logs, cracks, crevices, under the eaves of buildings.

At what temperature do insects stop moving? ›

Once development resumes in the spring, exposure to temperatures below 50°F can cause insects to enter a chill coma, where development and movement cease until favorable conditions resume. They can experience injury during this time, the extent of which depends on the duration and the temperature.

What weather do insects prefer? ›

Warm, dry weather is what bugs like best, although many of them need a plentiful water source to help them thrive as well. Insects are not able to generate their own body heat, so they rely on the warmth of the sun's rays to keep going.

How do insects survive hot weather? ›

Dormant During the Day

People and mammals also seem to lack motivation to move when it's hot. Dormancy allows insects to generate less of their own heat and conserve water. Insects can take it to the extreme with aestivation, which is the summer equivalent of hibernation.

How do insects survive extreme heat? ›

Insects are equipped with heat shock proteins, which help maintain bodily function when external stressors get extreme. During heat waves, they may increase the production of heat shock proteins in order to survive the high temperatures.

Do insects prefer heat or cold? ›

Warm, dry weather is what bugs like best, although many of them need a plentiful water source to help them thrive as well. Insects are not able to generate their own body heat, so they rely on the warmth of the sun's rays to keep going.

What is one effect of climate change on plants and animals? ›

Rising temperatures risk destabilizing the balance between wildlife and their ecosystem. As plants adapt to changing warming patterns, usually by blooming earlier or shifting to cooler locations, the wildlife that has adapted to them will be forced to face new environments.

What are the 5 effects of global warming? ›

Effects of Climate Change
  • Hotter temperatures. As greenhouse gas concentrations rise, so does the global surface temperature. ...
  • More severe storms. ...
  • Increased drought. ...
  • A warming, rising ocean. ...
  • Loss of species. ...
  • Not enough food. ...
  • More health risks. ...
  • Poverty and displacement.

What causes insect outbreaks? ›

Changes in climate, habitat, or community structure may provide an insect population with a reproductive opportunity that enables a rapid increase in population. Monoculture cultivation of crops and housing of livestock in modern rearing facilities are common practices in the US that lead to periodic insect outbreaks.

What is the biggest effect that climate change will have on human populations? ›

Climate change can also impact human health by worsening air and water quality, increasing the spread of certain diseases, and altering the frequency or intensity of extreme weather events. Rising sea level threatens coastal communities and ecosystems.

How does climate change destroy ecosystems? ›

The compounding effects of climate change are leading to many changes in ecosystems. Coral reefs are vulnerable to many effects of climate change: warming waters can lead to coral bleaching, stronger hurricanes can destroy reefs, and sea level rise can cause corals to be smothered by sediment.

What is the greatest threat to climate change? ›

The single greatest threat to human health from climate change will likely be the danger it poses to plants and our food security. Throughout the world, stable crops such as wheat, corn, and rice will be harmed by the combination of heat waves and drought associated with climate change.

What do insects need to survive? ›

The things insects need to survive are: food (protein), water, warmth during cold winter months, and shelter (from weather and predators). Different types of insects need different amounts of these elements and they obtain them in different ways.

Why do insects not like cold weather? ›

Insects are unlike mammals and birds because they must generate their own heat (called ectotherms). Insects die when they are exposed to temperatures below the melting point of their body fluids. If they want to survive our cold Iowa winters, they must avoid freezing or tolerate freezing.

What occurs to the growth and development of insects during high temperatures? ›

“First, warmer temperatures increase insect metabolic rates exponentially. Second, with the exception of the tropics, warmer temperatures will increase the reproductive rates of insects.

Is climate change causing more mosquitoes? ›

As the planet warms and climate change lengthens the mosquito season, the world's deadliest creature will expand its geographical range to new regions and re-emerge in areas where mosquito numbers had subsided for decades.

How has climate change increased the spread of disease through contaminated water sources and insects? ›

That's because climate change increases precipitation, storm surges, and sea temperatures. These environmental factors contribute to flooding and runoff that can spread sewage, chemicals and disease agents. They also favor the growth, survival and spread of bacteria, viruses and toxins created by harmful algae.

What does climate change have to do with spreading disease? ›

Climate change is causing milder winters, warmer summers, and fewer frost days. This change in climate makes it easier for many animals, mosquitoes, ticks, and the infectious diseases they spread to expand into new geographic areas and infect more people.

What are 3 factors that affect insect development? ›

The main abiotic factors influencing insects are temperature, moisture, light and air and water currents.

What factors affect insect growth? ›

The role of abiotic factors such as temperature, humidity, rainfall, light, and edaphic characters on growth, development, and the survival of insect at extreme climatic conditions is being explained. Distribution, dispersal, and migration of insects in relation to abiotic factors are dealt in brief.

What affects insect growth? ›

Hormones Responsible for Insect Growth & Development. Similar to humans, hormones are responsible for growth and development in insects. However, in insects, the two main hormones that trigger developmental changes are called ecdysone, a.k.a., the molting hormone, and juvenile hormone (JH).

Why does climate change cause insect outbreaks? ›

Temperature directly affects insect population dynamics through modification of developmental rates, reproduction and mortality. Weather can also affect insect populations indirectly via alteration of the abundance, distribution and physiology of host trees.

What are the effects of climate change on species distribution? ›

Climate changes can act to directly influence species distributions (e.g., drought, floods, wind) as well as indirectly (e.g., temperature and weather related changes in patterns of wildfire, insects, and disease outbreaks).

How does weather affect the timeline in the life cycle of insects? ›

Insects that are known to be most active in the warm months will not fair as well in the cold weather. This is especially true if the temperature falls below that of 50°F. If the temperature falls to freezing or below, cold-blooded insects will quickly become completely dormant.

How is climate change affecting populations of invasive species? ›

Climate change is creating new pathways for invasive species to be introduced, such as shipping routes that open up as sea ice retreats. Warmer temperatures can allow existing invasive species to expand their range into habitat that is currently too cool.

How does temperature affect insect activity? ›

Insects are cold blooded, and their metabolism and activity is very greatly influenced by the temperature of their bodies, which temperature is almost entirely dependent on that of the surrounding environment. A low temperature inhibits activity, and a higher temperature usually stimulates the animal.

Why are insects larger in warmer climates? ›

The combination of warm climates and moisture provides the perfect prerequisites for an abundance of food year-round. This constant access to nourishment has given many species of insects the ability to grow and flourish over years of development.

What temperature is too hot for mosquitoes? ›

Too Hot to Handle

But when the weather gets above 80 and into the 90s, then mosquitoes will become less active and seek shelter in the shade. However, the diseases they may be carrying will thrive in these high temperatures. The diseases will be more active in the heat and thus more transmissible.

How do insects survive extreme cold? ›

Many insects can gain shelter and nourishment through the winter in a variety of micro-habitats. Among these niches are under the soil, inside the wood of logs and trees, and even in plant galls.

Does keeping your house cold keep bugs out? ›

Some people may mistakenly believe that they can keep bugs out of their air conditioning system by keeping their homes cold. This actually does nothing to prevent bugs from trying to make their way through an AC. In fact, if it is extremely hot outside, bugs might even be more attracted to cooler air.

Why are bugs getting worse? ›

Key Takeaways. Due to climate change and global warming, pest populations are increasing, and people in and around Northern California (and around the globe) are seeing more bugs and pests during the summer months.

How does climate change affect mosquitoes? ›

Studies show that warmer temperatures associated with climate change can accelerate mosquito development, biting rates, and the incubation of the disease within a mosquito. The effect of climate change on the timing of bird migration and breeding patterns may also contribute to changes in long-range virus movement.

How does climate change affect the environment? ›

More frequent and intense drought, storms, heat waves, rising sea levels, melting glaciers and warming oceans can directly harm animals, destroy the places they live, and wreak havoc on people's livelihoods and communities. As climate change worsens, dangerous weather events are becoming more frequent or severe.

What keeps the bugs away the most? ›

Try natural repellants

Citronella, lemongrass, sweet orange, lemon eucalyptus, peppermint, lavender, and cinnamon are just a few of the oils known to repel summer bugs. There are several recipes available online for DIY bug repellants, yard sprays, candles, and diffuser blends.

Why are all the bugs dying? ›

Amid deforestation, pesticide use, artificial light pollution and climate change, these critters are struggling — along with the crops, flowers and other animals that rely on them to survive. “Insects are the food that make all the birds and make all the fish,” said Wagner, who works at the University of Connecticut.

What do bugs hate the most? ›

Lemongrass, citrus, peppermint, eucalyptus, tea tree, citronella, catnip, and lavender oils all possess properties that repel bugs. The oils can be used individually or combined to make a simple anti-bug potion. Mix about 1 cup of water with 25-30 total drops of oil into a small spray bottle.

Would the world be worse without mosquitoes? ›

And for millions of people who are infected by diseases mosquitoes carry, a world without mosquitoes would literally be life changing and life saving. Mosquitoes kill more people than any other species in the world, and half of the global population is at risk of contracting a disease from a simple mosquito bite.

What climate do mosquitoes hate? ›

Mosquitoes function best at 80 degrees F, become lethargic at 60 degrees F, and cannot function below 50 degrees F. In tropical areas, mosquitoes are active year round.

What climate do mosquitoes prefer? ›

Mosquitoes' Favorite Weather

They prefer to live in areas that are around 70-80 degrees Fahrenheit. So even though cold weather doesn't kill mosquitoes, they definitely don't like it. At around 60 degrees, they become lethargic and they are incapable of functioning at temperatures below 50 degrees.


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