10 Terrifying Human Encounters with Swarming Animals

Swarming is a fascinating yet unnerving phenomenon where animals move together en masse, often causing unintentional chaos for humans. Whether it’s birds, bees, or marine predators, swarming is typically a natural behavior tied to survival, such as migration, mating, or finding food. However, when these mass movements clash with human activities, the results can range from mildly inconvenient to downright terrifying.

Thanks to modern technology like smartphones and the internet, we’re more aware than ever of these extraordinary events. Videos and firsthand accounts show how swarming animals can unexpectedly disrupt daily life, sometimes causing panic or even endangering lives. From bats dive-bombing schoolchildren to a mouse plague ravaging Australian farms, these encounters remind us that nature is unpredictable and, at times, overwhelming.

Here are ten terrifying examples of human encounters with swarming animals that will make you think twice the next time you hear a buzz, splash, or rustle in the distance:

Related: Ten Frightening and Lethal Hamster Attacks

10 Bats Dive-Bomb Schoolchildren in Australia

Bats are remarkable creatures, the only mammals capable of sustained flight, but they can also be the stuff of nightmares when swarming in massive numbers. In the quiet town of Ingham, North Queensland, Australia, 300,000 bats descended without warning, disrupting daily life and sending residents into a panic. The invasion was so intense that some parents kept their children home, fearing for their safety.

For those who braved the chaos, the sight of bats dive-bombing students near an elementary school was unforgettable. Though bats rarely harm humans directly, their swarms can cause scratches or spread diseases like rabies and even deadly viruses such as Ebola. Victims often require rigorous medical care to prevent infection, making such encounters particularly traumatizing.

While bats play a vital role in ecosystems by controlling insect populations, their unexpected mass appearances are a chilling reminder of how nature can disrupt human routines.^[1]

9 Piranhas Kill Four People in Paraguay

Piranhas, notorious for their razor-sharp teeth and fearsome reputation, inhabit South American rivers and lakes. Though they’re not usually a threat to humans, swarming piranhas can turn deadly under the right conditions. In 2022, four men in Paraguay tragically drowned after being attacked by a swarm of these carnivorous fish while swimming in local rivers.

The pain of the bites caused panic, making it impossible for the victims to stay afloat. Their bodies were later recovered, covered in piranha wounds. These predators have an unparalleled bite force for their size, thanks to interlocking teeth designed for puncturing and shearing.

U.S. President Theodore Roosevelt famously dubbed the piranha “the most ferocious fish in the world” after a South American expedition in 1913. While this description may be exaggerated, it’s hard to argue against their fearsome capabilities, especially during such horrifying attacks.^[2]

8 Bee Attack Kills Man and Hospitalizes Others in Arizona

Bees are essential pollinators, but when they swarm, they can become a deadly force. In 2021, near Tucson, Arizona, a man tragically lost his life, and three others were hospitalized after stumbling into a bee swarm. Each victim endured hundreds of stings before emergency responders arrived. Even firefighters on the scene weren’t spared, with one requiring medical attention.

The swarm originated from an open hive in a nearby tree, highlighting the risks of unmanaged beekeeping in urban areas. Bee swarms often split from their colonies in search of new homes. While most pass without incident, accidental encounters like this can turn deadly, particularly for individuals allergic to bee venom.

This tragic event serves as a stark reminder of the importance of responsible beekeeping and the unpredictable dangers of nature’s tiniest creatures.^[3]

7 Grasshoppers Invade Las Vegas by the Millions

In 2019, Las Vegas found itself under siege—not by gamblers, but by 46 million grasshoppers. The swarm was so large it registered on weather radar, creating a surreal spectacle of insects buzzing around the city’s famous neon lights.

The invasion was triggered by an unusually wet July, which created ideal breeding conditions for the grasshoppers. Although these plant-eating insects caused minimal damage, the sheer scale of their presence disrupted daily life and startled locals and tourists alike. Green spaces bore the brunt of the invasion, but fortunately, Las Vegas escaped the widespread destruction associated with locust swarms.

While the event was mostly harmless, it was a vivid reminder that even the most modern cities are not immune to nature’s surprises.^[4]

6 Spider Crabs Swarm Beach in Cornwall

In 2022, just as locals in Cornwall began to recover from a rare shark attack, another unexpected invasion occurred—this time by thousands of spider crabs. The crabs gathered en masse on the beach, shedding their old exoskeletons and forming a protective “wall” while their new shells hardened.

Though these crabs are harmless to humans, their eerie, army-like appearance sent beachgoers fleeing. Rising sea temperatures due to climate change are making such swarms more common, turning routine beach days into scenes straight out of a science fiction movie.

The crabs eventually retreated to deeper waters, but their presence left a lasting impression on locals who thought the beach had finally returned to normal.^[5]

5 Feral Hogs Devastate Farms in New Mexico

In 2012, a swarm of feral hogs migrated from Texas into New Mexico, leaving a trail of destruction in their wake. These wild swine are notorious for their aggressive behavior and relentless appetite, and they wasted no time wreaking havoc on farms. They destroyed crops like milo, sorghum, and wheat, rooted up fields, and even attacked lambs and kid goats.

Frightened farmers were forced to abandon their properties as the feral hogs not only caused economic losses but also made farms vulnerable to theft by creating chaos. The swine posed an ecological threat, competing with native wildlife for food and water while spreading over 20 diseases, many of which can be fatal to livestock.

The invasion underscored the challenges of controlling feral hog populations, which continue to grow across the United States. These animals are more than just a nuisance—they’re an ecological and economic menace that farmers dread seeing on the horizon.^[6]

4 Australia’s Mouse Plague of 2021

Mouse plagues have plagued Australia for centuries, but the 2021 outbreak was especially devastating. After a prolonged drought, rains created the perfect conditions for mice to multiply, particularly in grain-growing regions of eastern Australia. Swarms of mice infiltrated homes, farms, and even hospitals, gnawing through wires, destroying machinery, and contaminating food supplies.

Traps and poisons were no match for the sheer number of rodents. Farmers watched helplessly as grain and hay stocks were decimated while industrial-scale traps proved ineffective. The situation became so dire that mice even bit patients in hospitals, adding a surreal level of horror to an already dire crisis.

While the government spends millions every few years combating these outbreaks with potent rodenticides, the 2021 plague serves as a grim reminder of how quickly nature can turn against us when conditions align in its favor.^[7]

3 Bees Chase Car for Two Days

Bees are fiercely loyal to their queen, as one grandmother in the UK learned in a bizarre two-day ordeal. After visiting a nature reserve, Carol Howarth unknowingly picked up a queen bee that clung to her car. Soon, an entire swarm of bees followed her vehicle through town, refusing to leave.

A ranger from the Pembrokeshire Coast National Park intervened, calling in local beekeepers to relocate the swarm. Although many bees were boxed and removed, they continued pursuing the car, likely drawn by pheromones left behind by the queen. The relentless pursuit only ended after more drastic measures were taken to disperse the bees.

This unusual incident highlighted the remarkable instincts of bees and their determination to protect their queen—even if it meant chasing a car for days.^[8]

2 Military Veteran Dies from Fire Ant Attack

Fire ants are infamous for their painful stings, which can cause severe allergic reactions and even death in extreme cases. In 2019, Joel Marrable, an Air Force veteran battling advanced lung cancer, tragically fell victim to a swarm of fire ants at a Georgia VA hospital.

Marrable, unable to defend himself due to his condition, was covered by ants twice—once in his hospital bed and again after being moved to another room. The repeated attacks proved fatal, and his death sparked outrage over the hospital’s failure to protect vulnerable patients from such preventable dangers.

This heartbreaking incident underscores the risks posed by even the smallest creatures when their swarms go unchecked, particularly in environments where safety should be paramount.^[9]

1 Swarm of Sharks Attack Surfers in Long Island

For beachgoers, few things are more terrifying than spotting a shark—but imagine encountering a swarm of them. On July 3, 2023, Long Island’s beaches became the scene of two separate shark attacks on surfers. Although the victims suffered injuries to their feet, thighs, knees, and hands, they were lucky to escape with their lives.

Subsequent drone surveillance revealed a swarm of approximately 50 sharks hunting prey near the coast. The discovery prompted increased patrols and surveillance, ensuring beachgoers were warned of potential dangers.

While shark swarms are rare and injuries even rarer thanks to modern monitoring systems, the Long Island attacks serve as a stark reminder of nature’s unpredictability—and the primal fear these apex predators inspire.^[10]