Some people living in Japan think cockroaches are the worst house invaders—until a six-inch horror creeps out from behind the TV, sizes you up and vanishes into the darkness. That’s the Japanese huntsman spider (アシダカグモ, ashidakagumo), literally “long-legged spider.” Then you get to enjoy the wonderful feeling of knowing it’s just… somewhere in your house. That’s right—Australia doesn’t have a monopoly on nightmare fuel.
But what is the Japanese huntsman, really? Should you be worried about something that big living in your home rent-free? Is it truly the chill, bug-munching roommate that spider bros on Reddit keep trying to gaslight you into loving? Let’s investigate—from a safe, broom-length distance.
What the Hell Is That?
If you’ve ever spotted a giant, long-legged spider darting across your ceiling at 1 a.m., chances are you’ve met the ashidakagumo. Despite its size and speed, this spider isn’t really dangerous—it’s just big, fast and understandably horrible.
The ashidakagumo is Japan’s largest species of wandering spider. This means it doesn’t build webs to catch prey. Instead, it actively roams around looking for insects, usually at night.
Males typically have a body length of 1.5 to 2 cm, while females can reach 2.5 to 3 cm. But don’t be fooled by those measurements—when you factor in their long legs (up to 10–12 cm tip-to-tip), they can easily cover the size of an adult’s palm—or your face.
They’re primarily found in regions south of Ibaraki Prefecture and are more common in western Japan. But their habitat range has slowly crept northward (due to climate change), so if you haven’t seen one there yet, you just might soon.
And don’t think you’re safe just because you live in the city. I was once trapped in my Tokyo apartment for two days because one took over my genkan (entranceway). After moving to Kanagawa, it’s been like living in The Babadook—every time I walk into a room, I catch myself slowly tilting my head up, bracing for a face-to-face encounter.
These nocturnal spiders hide during the day and become active after dark. If you’ve spotted one in your bathroom or kitchen, it’s not there for you—supposedly—it’s hunting.
Huntsman spiders in Japan are not venomous (to people), don’t spin sticky webs around your furniture and don’t pose any health risks to humans. That said, it’s entirely understandable to “nope” out of the house when you find one.
Most Common Prefectures and Regions
While ashidakagumo can appear in nearly any part of Japan, they’re especially prevalent in central and southern prefectures with warmer, humid weather, older infrastructure and a steady supply of bugs. In colder, snow-heavy areas like Tohoku and Hokkaido, they’re rarely seen and unlikely to survive the winter indoors.
- Tokyo and Kanagawa: Common in older apartment buildings, especially near river-adjacent neighborhoods, where bugs are abundant. More frequent in ground-floor units and houses with poor insulation.
- Chiba, Saitama and Gunma (Greater Kanto): Seen in suburban homes and areas with dense vegetation. Gunma’s humid summers and older wooden houses make it a seasonal visitor.
- Osaka and Kyoto: Found in dense urban areas and surrounding suburbs like Hirakata, Takatsuki and Uji. Kyoto’s traditional wooden homes are particularly welcoming to them.
- Shizuoka, Aichi, Gifu and Mie (Chubu region): Frequent in coastal and countryside homes where insects are plentiful. Milder winters allow for year-round survival indoors.
- Wakayama and Nara: Appear regularly in rural homes, coastal towns and older buildings with easy insect access. Humidity and warmth make ideal conditions.
- Fukuoka and Kyushu region (e.g., Kumamoto, Miyazaki, Kagoshima): This area’s warm, moist climate and traditional housing styles make it a hotspot.
- Okinawa: Extremely common year-round due to the subtropical climate. They’re practically locals.
Why Is It in My House?
As horrifying as they look, Japanese huntsman spiders are surprisingly useful to have around—if you can stomach their presence.
Ashidakagumo are natural-born exterminators. They feed on all the things you don’t want in your home: cockroaches, flies, centipedes, mosquitoes and basically anything that scurries, buzzes or lays eggs in your sink. There are even stories of larger ones preying on mukade (venomous centipedes), geji-geji (house centipedes) and even baby mice—though let’s not picture that too clearly.
In Japan, they’re considered beneficial insects, and some folks have even given them a nickname: “Sergeant Ashidaka.” Not out of affection, necessarily, but out of respect. These spiders do the dirty work that most of us can’t—or won’t—deal with, especially in older homes where pest control is a never-ending battle.
Even better, their presence can help reduce your need for chemical insecticides. No poison, no sticky traps—just one unsettling creature silently handling your cockroach problem while you try not to make eye contact with it.
So yes, they’re creepy. But they’re also quietly doing you a favor. Probably. Or so the spider bros will always tell you when one of these shows up in a Japan subreddit.
Can I Squish It?
I wouldn’t recommend it. If you squish an ashidakagumo, congratulations—you might have just discovered what we call “f### around and find out.” That big ol’ spider may have been a mama carrying 100+ spiderlings like a nightmare piñata. Smash her, and suddenly your quiet night turns into a hundred reasons for regret.
Okay, But Seriously, How Do I Get It Out of My House?
Not everyone is emotionally prepared to coexist with something that moves and looks like a facehugger from Alien. If the ashidakagumo has overstayed its welcome, there are humane and practical ways to show it the door.
Start with the classics: bowl and cardboard (for the bold) or broom and dustpan (for the rest of us). Guide it toward a door or window and let it escape. They’re usually more interested in running from you than at you. But it sure can feel like the latter.
In fact, the ashidakagumo will rear up and display a defensive posture if it feels threatened. I honestly can’t think of anything worse than poking one with a broom, only for it to raise its legs like it’s asking if I have a problem.
How to Get It Out (Gently)
- Trap it under a cup or bowl and slide a piece of cardboard or paper underneath.
- Use a long-handled broom or dustpan to encourage it toward an open window or door.
- If you must, gently sweep it into a box and carry it outside.
How to Keep It Out
- Seal gaps around windows, doors, pipes and AC units.
- Clean regularly—especially behind and under appliances.
- Take out the trash and avoid leaving food scraps or cardboard lying around.
- Fix leaks or damp spots that attract pests (and, by extension, spiders).
- Reduce clutter in storage areas and closets.
- Use natural repellents like citrus oil, peppermint or vinegar sprays near entry points.
If you really can’t deal with it, professional pest control (害虫駆除, gaichu kujo) in Japan does handle spiders—but it’s rarely necessary unless you’re dealing with an actual infestation (which huntsman spiders usually help prevent, not cause). You can also try spider repellent (クモ忌避剤, kumo kihi-zai) around your doors and windows.
But remember: if you remove the spider but leave behind its food supply—cockroaches, flies and other creepy crawlies—don’t be surprised if another one drops by for dinner.
Are you a spider bro? Do you jump at the chance to let everyone know that you give your resident ashidakagumo pet names and let them crawl around your home? Let us know in the comments.
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When I first came to Japan, I lived in an old Japanese house next to a bamboo forest in Kamakura. I didn’t speak any Japanese but the first words I learned were cockroach, centipede, millipede, and spider. There were five ashidakagumo in my room! At first I was terrified but gradually began to realize they had personalities and were avoiding me as much as I was avoiding them. Now I live in Tokyo but there are a few ashidakagumo of various sizes. I would much rather have them in my house than cockroaches, centipedes, and millepedes.
Been in Okinawa since 2012. Haven’t seen one yet. Hadn’t even heard of them being here. Had one in my apartment when I lived in Australia, though.