About an hour from Vienna, the Penny Markt in Krems an der Donau is renowned for its low prices and locally sourced meat and fresh produce. However, one mild August day last year, shoppers searching for bargains were startled to find a more exotic and unwelcome guest hiding among the banana crates.
The intruder was a Brazilian Wandering Spider, an 11cm black and red arachnid whose bite can cause convulsions, hypothermia, death, and—if you’re a man—a particularly painful case of uncontrolled erections. The surprise was understandable.
The store closed for precautionary disinfection, and the spider vanished, never to be seen again. This incident is just one of many recent invasive creepy crawly stories making headlines in Europe.
France has gained an unfortunate pre-Olympic reputation for rampant bed bug infestations, with Paris deputy mayor Emmanuel Grégoire warning that “no one is safe. You can catch them anywhere,” and reports of the bloodsuckers on the Eurostar causing panic in London.
Tiger mosquitoes, which can transmit Dengue and Zika, have also been spotted around the country, prompting Paris authorities to enlist entomologist ‘detectives’ to locate their breeding sites.
Meanwhile, the Turkish pharmaceutical industry sees Europe as a promising new market for scorpion antivenom.
Is climate change responsible for this apparent influx of arthropods?
The situation is less dire than the headlines suggest, says Dr. Matt Green, principal entomologist at Rentokil Initial, a UK-based global pest control company with operations across Europe.
Dengue is far from becoming endemic. The rise in French bed bug reports is largely due to increased vigilance following alarming headlines. Most invasive species are not appearing due to rising temperatures.
“I’m often asked how climate change affects our business. Given that humans have already transported all major pests to nearly every country and major human center, the impact is not as significant as you might think,” Green tells Fortune.
Is climate change to blame for this apparent arthropodal invasion?
The good news for those worried about encountering Brazilian Wandering Spiders is that they can relax.
Most species need more than just a rise in temperatures to settle in new, very different ecosystems. For instance, the Sheerness docks near London have had a population of 10,000 yellow scorpions for centuries, brought over by merchant ships from continental Europe, but these harmless creatures haven’t spread because the conditions aren’t suitable.
The Impact of Climate Change on Europe’s Pest Population
This doesn’t mean climate change isn’t affecting Europe’s pest profile.
Termites, historically a problem in Mediterranean countries, are now making their way into Northern Europe due to rising temperatures. However, the relative lack of timber buildings means they’re unlikely to cause widespread economic damage.
Aedes mosquitoes, including tiger mosquitoes, are well-established in Italy and increasingly in France, suggesting countries like Switzerland may not be spared. “Europe is already seeing how climate change is creating more favorable conditions for invasive mosquitoes to spread into previously unaffected areas,” Andrea Ammon, director of the European Centre for Disease Prevention and Control, told the BBC.
Fortunately, these mosquitoes do not carry malaria, as Anopheles mosquitoes do, which is unlikely to spread in Europe due to the lack of large bodies of standing water needed for breeding.
However, Asian hornets could soon become a common sight, depending on where you live. “They’re moving through France easily, and there have been instances of them overwintering in the U.K. This means we’ve probably got them now, so make your peace with it,” says Green.
Bed bugs are another concern. Even before the recent surge, infestations were costing the French economy €230 million ($246 million) annually, according to the health agency Anses. Treatments and lost income can cost hotels thousands of dollars and may create hysteria during the Paris Olympics. These pests thrive in warmer weather. “When the temperature inside your house is 25 to 26 degrees Celsius (77 to 78.8 Fahrenheit), bed bug eggs hatch in just five days. At 20 degrees Celsius, it takes 10 days,” Jean-Michel Bérenger, an entomologist and co-founder of the National Institute for the Study and Fight Against Bedbugs, told Wired last year.
Changes in Europe’s Pest Populations Beyond Climate Change
Whether aided by rising temperatures or not, the pests most likely to proliferate are those best adapted to humans and our behavior—and it’s our behavior that helps them spread.
In rural areas, this often happens through monocultural agriculture or the importation of non-native plants. The oak processionary moth, a species native to Southern Europe that damages forests and releases irritating hairs, established a foothold in the U.K. in the 2000s after an oak was imported from Europe, ironically near the Royal Botanical Gardens at Kew.
Urban pests are more noticeable. Rats, mice, and cockroaches are perfectly suited to living closely with humans, whether we like it or not. They’re small, can crawl through tight spaces, are generally nocturnal, and are omnivorous. “They’re massively flexible, so they won’t care about a one or two-degree change in temperature. They’re already living in air-conditioned buildings,” says Green. “Some moths in warehouses barely fly these days. They don’t have to. They live in a world full of food, getting moved around by humans. It’s a great life.”
Changes in human behavior, even well-intentioned ones, can also help urban pests proliferate.
Despite the media frenzy, bed bug populations did increase rapidly worldwide in the early 21st century. In Australia, the rise was between 500% and 4,500%; in New York City, bed bug complaints jumped from 537 in 2004 to 10,985 in 2009, though they have since decreased.
Entomologists attribute this resurgence to the end of the DDT era—the infamous insecticide significantly reduced global insect pest numbers in the mid to late 20th century. After its use was discontinued due to environmental and health concerns, species began to develop resistance. Essentially, we’re returning to historical norms from a period of unusually low insect activity.
This situation is unlikely to change. Although the pest control industry is using increasingly sophisticated monitoring strategies and ‘physical’ interventions like steam cleaning for bed bugs, moving away from chemical controls means losing a powerful weapon against infestations.
A similar situation may arise with rats in Europe, where regulators are increasingly restricting anticoagulant rodenticides. While this may be for good reasons, it has pest controllers worried. One commented, “There’s a whole generation of pest controllers trained to put rat poison into bait boxes. If you take that away, what do you have left? To quote Aliens, what are we supposed to use, harsh language?”
The Future
Human activity has led to the extinction of many species, often unintentionally, and continues to do so. However, the pests we wish to see less of have proven resilient. Almost by definition, pests thrive alongside human activity.
So, what can we expect? In Europe, climate change and human activity are unlikely to make lethal spiders a regular grocery store occurrence or bring tropical levels of mosquito-borne diseases.
But they will alter the fauna we share our environment with. Get used to Aedes mosquitoes and Asian hornets; be vigilant for rats and bed bugs.
What may change the most is our expectation of what pest control means. With the spray-it-first-ask-questions-later approach consigned to history, eliminating pests at first sight may become a relic of the 20th century.
