This summer, people across the UK may be noticing more dead bumblebees on the pavement than usual, and scientists say there is a reason behind the phenomenon.

The pattern results from a combination of naturally short life cycles, elevated temperatures, and long-term changes in land use, according to Senior Lecturer in Zoology Alex Dittrich of Nottingham Trent University, who explains that extreme heat, pesticides, habitat loss, and other environmental pressures can make survival more difficult for these important pollinators.

Bumblebee workers usually only live for four to six weeks. The colony is arranged to allow this turnover; if a worker dies, the other bees in the hive remove the body to prevent the spread of disease. It is therefore not uncommon to find dead bees on sidewalks. Although this rate of death is normal, further environmental stressors can make survival even more difficult.

A Summer of Record Heat

June recently saw the warmest temperatures ever recorded in England, while the UK as a whole experienced its second-highest June temperatures on record. High temperatures affect bumblebees by interfering with their development, reproduction, and ability to fly.

These temperatures can also push colonies beyond the limits of their natural cooling mechanisms; although bees keep the temperature inside the hive down by waving their wings, this method is only effective up to certain temperatures, and prolonged heat exposure can alter development and threaten long-term population stability.

Higher temperatures also interfere with the timing of biological events. Climate change can also contribute to phenological mismatch, in which species that depend on one another become out of sync with seasonal changes. For instance, bees might emerge from hibernation before flowers are available, or flowers may bloom and then die off before the bees are active. In these situations, the bees are left without access to nectar at crucial times.

Pesticides Compound the Problem

Chemical exposure also affects bumblebee populations. Although the EU and UK have banned the most harmful neonicotinoids, other insecticides like organophosphates, synthetic pyrethroids, and phenylpyrazoles are still widely used. These chemicals can paralyze or kill bees and also interfere with their ability to navigate. Herbicides can also reduce the availability of important food sources, such as dandelions, which are a major source of nectar at the beginning of the season.

Habitat loss also makes these problems worse. Housing development, intensive agriculture, and road construction have reduced the amount of natural land available for bees to nest and find food. The loss of these habitats reduces the ability of bee populations to cope with extra stress caused by heat and chemical exposure, worsening the impact of their naturally brief lifespans.

Why It Matters Beyond the Garden

The number of European wild bee species considered at risk of extinction has increased from 77 in 2014 to at least 172 now, about 10% of the total species assessed. Bees pollinate an estimated 75% of global crops and play a significant role in pollinating nearly 90% of flowering plants.

Dittrich suggests leaving the herbicide out when dealing with dandelions, letting parts of the lawn grow uncut, planting native species, and exploring non-chemical pest-control options first, using chemical treatments sparingly. For a bee struggling on hot pavement, a mixture of two parts sugar to one part water can help revive it. If it is safe to do so, people can also move the bee to a shady spot or flower.

While these measures will not eliminate the wider pressures affecting bumblebees, they can reduce some of the stressors that make it harder for them to survive. As temperatures rise and habitats keep changing, it will become more important to ensure that bees have reliable sources of food and shelter.

Austin Burgess is a writer and researcher with a background in sales, marketing, and data analytics. He holds an MBA, a Bachelor of Science in Business Administration, and a data analytics certification. His work focuses on breaking scientific developments, with an emphasis on emerging biology, cognitive neuroscience, and archaeological discoveries.

Up to 36 per cent of animal habitats on land could be exposed to multiple extreme climate events

Fog is a living ecosystem for bacteria, rather than just a sterile cloud of mist,  and may provide an unexpected buffer against harmful pollution.

In a recent paper published in mBio, an Arizona State University team led by then PhD candidate Phi Thuong Thuong Cao, now a graduate, revealed that bacteria are present in fog that cleans the air at a surprising rate, but also poses a possible risk to drinking water collection.

While scientists have long known that bacteria exist in fog, the researchers were surprised to find that the bacteria are not merely present but form an active, if short-lived, ecosystem.

Investigating the Mysteries of Fog Bacteria

“There’s very limited knowledge about what kinds of bacteria are present in fogs, which are like clouds at the ground level,” Cao said.

To probe the mystery of fog bacteria further, Cao focused on two questions: what kinds of bacteria are present, and whether they are active. Discovering growing bacteria within fog droplets elevates fog from a simple atmospheric phenomenon to a biological habitat, a major shift in how researchers have traditionally viewed it.

Fog is composed of tiny droplets of water, each less than a tenth the width of a human hair and too small to fall to the ground. These minuscule droplets form around particles, which can occasionally be living microbes. Although fewer than 1% of droplets contain bacteria, that still represents a substantial population, with bacterial concentrations roughly comparable to those found in the ocean. About 10 million individual bacteria inhabit just a thimbleful of fog water.

A major challenge in studying fog is the wind. Sampling the same location before, during, and after a fog event can produce misleading results because airborne particles are constantly being transported and mixed. For this reason, Cao focused on radiation fog, which forms in still air near the ground as temperatures cool. This allowed the team to minimize complications associated with sample collection.

Standout Bacteria

In Cao’s investigation, one particular type of bacteria, methylobacteria, predominated within the fog droplets. Intriguingly, samples collected during fog events contained far more bacteria than samples of dry air gathered beforehand, suggesting that these microbes thrive in foggy conditions. Among the compounds methylobacteria consume are simple carbon-based molecules, including pollutants such as formaldehyde. In a laboratory setting, Cao was able to observe and experiment on samples collected in the field.

“We observed them under the microscope to see that, yes, the bacteria are getting bigger, and they’re dividing, so there is growth,” Cao explained. “We also found that they’re using the formaldehyde as food to support their growth.”

Even more surprising was the rate at which methylobacteria were breaking down formaldehyde—far faster than they could consume it. This led the team to conclude that because formaldehyde is toxic to the bacteria, they were converting much of it into carbon dioxide to make their environment safer, doing so even faster than they could use it as a food source.

Potential Hazards

The team’s research suggests that fog may play a more important role in Earth’s ecosystems than previously understood, serving as both a temporary aquatic habitat and a natural filter for harmful pollutants.

The implications of the findings are varied. Harvesting fog for drinking water and crop irrigation is already practiced in some regions of the world. This study suggests that such water may contain more bacteria than previously recognized, potentially requiring additional filtration. The risk to most people appears minimal; researchers say only a slight risk may exist for individuals with severely compromised immune systems who are exposed to fog. However, more work is needed to determine the potential benefits and drawbacks of consuming water collected from fog.

Harvesting fog for drinking water and crop sustenance is an ongoing practice. This work shows that water may be full of bacteria, requiring more filtering than previously understood.  The risk to most people is very minimal; only a minor risk exists to people with heavily compromised immune systems from breathing in fog. However, the researchers say that more work is needed to determine the benefits and harms of drinking fog water.

“It’s relatively new that people are starting to look at biological activities in clouds, so there’s still a lot which we don’t understand,” said co-author Pierre Herckes. “At nighttime, for example, there isn’t that much atmospheric chemistry going on. Chemistry is largely driven by the sun and by light. But if the bacteria are still doing their thing even during the nighttime, they can be important.”

Many questions remain unanswered in the wake of this discovery. Cao’s team focused on a single type of fog, leaving open which bacteria thrive in other kinds of fog in other locations, what they eat, and how they impact air quality, all of which will require further study.

“The sky’s the limit,” co-author Ferran Garcia-Pichel says. “No pun intended.”

The paper, “Growth and Formaldehyde Degradation of Photoheterotrophic Methylobacterium within Radiation Fogs,” appeared in mBio on May 11, 2026.

Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.