Incredible photos show an extraordinary number of insects wreaked havoc on drivers, closing a bridge and causing accidents on the weekend.
The Aigiōhashi Bridge, which stretches over the Kiso River, connecting Gifu and Aichi Prefectures, was a scene of chaos on the weekend, as swarms of mayflies descended on the area, piling up on the road in a one-centimetre thick layer, creating a slippery surface that posed a danger to drivers.
愛岐大橋やばい😨😨😨 pic.twitter.com/hkCBDakvcY
— りょうた (@ryotan1206) September 11, 2016
These photos, taken when the incident occurred, on the night of Saturday 11 September, show just how treacherous driving became, with driver visibility obviously affected.
虫大量発生
— sslogic (@sslogic) September 11, 2016
愛岐大橋渡らない方がいいかも pic.twitter.com/KTsQo5sETs
The slippery surface posed such a risk to drivers that the bridge was closed temporarily. According to officials, a rear-end collision involving several vehicles occurred on the bridge while the insects were falling in the area.
愛岐大橋ヤベェんだけどwwww
— おーほり (@12kuro12) September 11, 2016
でっけぇ羽虫みたいなのが竜巻みたいに発生してて対向車線事故ってめっちゃ渋滞してる pic.twitter.com/TXyxpiCMKU
Drivers and passengers were shocked by what they saw, with many people sharing photos of the situation on Twitter.
約4時間前の愛岐大橋の話し。
— 元気理容師 かなパー (@chokikana) September 11, 2016
ウスバカゲロウの大量発生∑(゚Д゚)
ひとつ北のライン大橋もこんな感じだったそーで pic.twitter.com/ll6WaaX4bd
▼ From this angle, it looked like insects were falling from the sky.
https://twitter.com/R____piyo/status/774930997976502272▼ At one point, the insect cover looked like snow.
愛岐大橋でウスバカゲロウ大量発生で追突事故してる!!やべぇ pic.twitter.com/XO82WLakTF
— ともや。アコギ弾き語り (@tomoyaT314e) September 11, 2016
Police were on hand to help guide drivers safely across the bridge. It couldn’t have been a pleasant job being out there amongst all those mayflies!
いいですよー! pic.twitter.com/aoPbUfNGJl
— りょうた (@ryotan1206) September 11, 2016
According to officials, mayfly swarms of this magnitude have not been seen in recent years. While the rear-end collision and the long traffic jam leading up to the bridge caused long delays, thankfully no injuries were reported.
Source: Hachima Kikou
Top Image: Twitter/@sslogic

Driver who killed cyclist in crosswalk accident found not guilty, causes controversy in Japan
Tokyo snowfall, the heaviest in four years, causes chaos in the capital 【Photos】
Osaka governor calls president of Earth to deal with swarms of Expo bugs
Man jumps off bridge in Osaka to celebrate Heisei era’s end, hits something other than water【Vid】
Shinkansen breaks down, causes all-day commuter chaos at Tokyo Station
Japan has only one airport named after a samurai, so let’s check out Kochi Ryoma【Photos】
Japan’s new “Cunte” contact lenses aren’t pronounced like you’re probably thinking they are
Japan Extreme Budget Travel! A trip from Tokyo to Izumo for just 30,000 yen [Part 1]
7-Eleven Japan’s sakura sweets season is underway right now!
Ghibli’s Kiki’s Delivery Service returns to theaters with first-ever IMAX screenings and remaster
Family Mart’s Shibuya Cat Street shop hosts first-ever rescue cat photo exhibition for Cat Day
Beautiful 3-D puzzle kit lets you build Ghibli’s Spirited Away bathhouse with no tools, glue【Pics】
Haku is…Chihiro’s dead brother? Studio Ghibli fans blown away by Spirited Away theory
Brand-new Cardcaptor Sakura Cafe opens in Tokyo this week, with Kero-chan calling the shots
Muji releases ice creams with special ingredients for summer in Japan
The 10 most annoying things foreign tourists do on Japanese trains, according to locals
Starbucks Japan releases new sakura goods and drinkware for cherry blossom season 2026
Is Sapporio’s Snow Festival awesome enough to be worth visiting even if you hate the snow? [Pics]
Japan has trams that say “sorry” while they ride around town…but why?
Tokyo Skytree turns pink for the cherry blossom season
Highest Starbucks in Japan set to open this spring in the Tokyo sky
Shibuya Station’s Hachiko Gate and Yamanote Line stairway locations change next month
Yakuzen ramen restaurant in Tokyo is very different to a yakuza ramen restaurant
Starbucks Japan adds new sakura Frappuccino and cherry blossom drinks to the menu
Japan’s newest Shinkansen has no seats…or passengers [Video]
Foreigners accounting for over 80 percent of off-course skiers needing rescue in Japan’s Hokkaido
Super-salty pizza sends six kids to the hospital in Japan, linguistics blamed
Starbucks Japan unveils new sakura Frappuccino for cherry blossom season 2026
Foreign tourists in Japan will get free Shinkansen tickets to promote regional tourism
Take a trip to Japan’s Dododo Land, the most irritating place on Earth
Naruto and Converse team up for new line of shinobi sneakers[Photos]
Is China’s don’t-go-to-Japan warning affecting the lines at a popular Tokyo gyukatsu restaurant?
Survey asks foreign tourists what bothered them in Japan, more than half gave same answer
Japan’s human washing machines will go on sale to general public, demos to be held in Tokyo
Starbucks Japan releases new drinkware and goods for Valentine’s Day
We deeply regret going into this tunnel on our walk in the mountains of Japan
Studio Ghibli releases Kodama forest spirits from Princess Mononoke to light up your home
Major Japanese hotel chain says reservations via overseas booking sites may not be valid
Put sesame oil in your coffee? Japanese maker says it’s the best way to start your day【Taste test】
No more using real katana for tourism activities, Japan’s National Police Agency says
MariCar Mario Kart driver mounts pavement, causes serious damage in Tokyo accident
W.T.F. Japan: Top 5 creepiest Japanese insects 【Weird Top Five】
Praying mantis in Japan hitches a ride, does a little dance for his driver【Video】
Pileup on sushi conveyor belt causes chaos for diners at restaurant chain in Japan
Elderly woman drives at speed on sidewalk in Japan 【Video】
Carlos Ghosn leaves jail in workman cosplay, causes hilarious Twitter storm in Japan
Typhoon warning from NHK Japan “to all foreigners” causes controversy online
Man stops train from leaving station in Japan, video goes viral online