Let’s rock.
It is a cruel fact of life in Japan that the more you want to open all the windows in your apartment, the more the bugs want to come inside. This is a field guide to insects you may encounter, what to do when you encounter them, and how to encounter them less often in the future.
For convenience’s sake, we’ve sorted them into generic home pests, bugs you may see while out and about, and three that might land you in the hospital.
Throughout the article we also have pictures of helpful products and bug specimens. If you happen to have your own product recommendations or stories of creepy crawly terror, do share in the comments.
So, grab some bug spray and let’s dive on in!
Home Pests
Cockroaches (ゴキブリ gokiburi) : Cockroaches love moisture and garbage. Given the humid climate of Ishikawa, roaches can flourish if you (or a neighbor) aren’t good about keeping your living space clean. If you find roaches in your apartment, you can pick up a ゴキブリホイホイ (gokiburi hoihoi, roach motel) at any department store or home center. Surviving in Japan Without Much Japanese has a comprehensive list of products for dealing with cockroaches.
House Centipedes (ゲジゲジ gejigeji) : Sometimes people confuse these creepy but harmless critters for the more dangerous mukade (see later). Gejigeji eat cockroaches and small spiders, so if they show up in your house, that means you have some other problems crawling around. While gejigeji do have weak venom, their teeth are not strong enough to get through human skin. Stings are basically unheard of–some people even keep them as pets or natural pest control.
If cockroaches are a warning a to keep your place clean, gejigeji are a cosmic intervention.
Ants (アリ ari) : Ishikawa doesn’t have any stinging ants, so no worries there. If there are ants in your home, you can buy products like アリの巣コロリ (ari no su korori), a plastic trap full of poison pellets that the ants will take back to the nest.
Termites (白蟻 shiro ari): If you live in a small apartment building or house, you might want to check for these every once in a while. One ALT found them in a small crawlspace under her first floor apartment, but only after they had chewed through a central pillar and hatched larvae. Usually they are light-colored, but in May, when they move nests, they turn black and look like winged regular ants. If you see them in your building, tell your landlord and your supervisor and prepare to have your place fumigated.
Tatami Bugs (ダニ dani) : Previous bloggers have posted on dani prevention and how to deal with dani in your house.
Rice Weevils (米食い虫 komekuimushi) : These little black weevils like to lay eggs inside improperly stored rice. Keeping your rice in sealed containers goes a long way to preventing them, but to keep your rice extra safe, invest in a chili oil capsule (it looks like a red, plastic chili pepper and is sold near rice in grocery stores) and toss it in the container, too. This will keep your rice bug free and won’t change the flavor.
Out and About
Mosquitoes (蚊 ka): Stagnant water in rice paddies and canals provides ample breeding ground for mosquitoes. Pharmacies stock all sorts of products for dealing with them and their bites. 虫よけ (mushi-yoke) is the word to look for in prevention. You can buy 虫よけ air fresheners, tissues, sprays, incense, bracelets, and even cases of repellent to stick on your screen door.
These last 120-200 days and cover one 6-8 tatami mat sized room.
If the mosquitoes still eat you alive, pharmacies have tons of creams. 虫刺され (mushi-sasare) is the word to look for. Surviving In Japan Without Much Japanese has guides to both Mosquito Repellents in Japan and Mosquito/Bug Bite Creams.
Cicadas (ゼミ zemi): The high-pitched hum of cicadas is a part of Japanese summer that you either love or hate. While obnoxious when they show up on your balcony, the only harm these bugs can really do is to startle you by flying into your face.
Spiders (クモ kumo) : Spiders in Japan can get big, but they are not known for being aggressive or venomous. Even the spindly, multicolored jorougumo is harmless. Stores sell spider (and other bug)-repelling chalk (pictured on the left) that you can apply to door and window frames to deter them from coming inside. Screen doors are popular spots for spiders to deposit egg sacs, so checking your balcony and windows every so often can spare you some panic later on.
Bumblebees and Hornets (花蜂 hanabachi for bumblebees and バチ bachi for hornets) : Like spiders, these may be bigger than you are used to in your home country. Bumblebees are large and loud, but not aggressive toward humans. Normal hornets can get 2 to 3 cm long. You can buy sprays for hornets’ and wasps’ nests at drugstores or home stores. If you get stung, look for 虫刺されクリーム (mushi sasare kuriimu) or 虫刺され薬 (mushi sasare kusuri). Any extra strength bug bite cream with ステーロイド (steroids) will help with inflammation.
The Big Bads
Tangling with these three bugs can put you in the hospital. The more rural/mountainous your area, the more likely you are to come across them. Use caution and it probably won’t be a big issue.
Pine Processionary Caterpillars (毛虫／ケムシ）
These have no common, species-specific Japanese name–try 刺毛ある毛虫 (shimou aru kemushi, literally “hairy caterpillars with stinging threads”) if you have to describe them. In late spring, these harmless-looking fuzzy caterpillars travel in neat lines to find pine trees to inhabit. More info is here.
Photo taken in Ishikawa.
Why worry?
Their hairs are an extreme irritant, and even brief contact with one hair can give someone weeks of a painful, itchy rash. In rural parts of the Noto, they have processed right through the balconies of former JETs. Once they find a pine tree, a strong wind can blow them or their hairs onto an unsuspecting victim.
If they’re on your balcony:
Close your doors and block off your AC unit. Call your supervisor and have them call in the professionals. After they leave, you may have to don a disposable rain suit and gloves and hose off the area. Do not touch them. If a hair gets on your skin, go to a doctor so they can prescribe you a steroid cream for the itching. Some over-the-counter bug creams also work on inflamed areas–look for 毛虫／ケムシ (kemushi) on the label.
Mukade (ムカデ) :
The most commonly spotted of the three. If you live in a rural (or even semi-rural) area or near a mountain, you may have to deal with a mukade at school or home. These giant centipedes have yellow legs, black abdominal sections, and red heads with oddly appropriate curly horns.
A particularly large specimen. They are usually about thumb-sized.
They like to find dark places to hide and have been known to lie waiting in futons and clothing. They’ve also been spotted in sink traps, bathroom drains, and on tree trunks. Folk wisdom is that they come in pairs.
If you are bitten:
While the venom is not fatal, it does cause a lot of pain (likened to an electric shock) and severe, persistent swelling. If you are bitten on a limb, ice it and see a doctor the next day. As with bee stings, some of the stronger 虫刺され medicine is marked for use on mukade bites, so that can hold you over until you see a doctor. If you are bitten on the head, neck, or chest, you should seek medical attention immediately.
If they are in your school, in your apartment, or crashing your picnic:
Mukade are not reviled for their looks alone–they are aggressive, fearless, and distressingly tough. Your best bet is to immobilize it with bug spray or head trauma and then sweep/toss it away. Killing them by squishing, while therapeutic for you, can release pheromones that attract more. It may continue to move even after bisected. Show no mercy, for mukade know none.
Giant Asian Hornet (スズメバチ suzumebachi）:
Do not attempt with live hornet.
Rural Japan has bugs, but it also totally has these!
Ishikawa JET 
Have yet to encounter most of the stuff here but I live every day of summer in fear nonetheless. I’ve definitely stocked up on quite a few bug products since getting here.
I think if I saw any of these in my apartment, I would leave and never return. I live in eternal fear of mukade and gejigeji to the point where I will check the surrounding area for them before settling down.
Note: I still haven’t seen any of those scary bugs.
Second note: That doesn’t make me any less fearful. I can’t let my guard down.
I live in Kyoto and often go rock climbing in the mountains north of Kobe (Rokkosan particularly). If you want to see suzumebachi, that’s the place! Loads of the bastards – terrifying!
The reason I ended up here, though, was due to seeing a suzumebachi today in downtown Kyoto! Keihan Marutamachi station, to be exact, just hanging out around the entrance stairs. Not what I wanted to see!
Hilariously my girlfriend (who is Japanese) is pretty calm around suzumebachi but is terrified of moths and butterflies. Go figure.
Heading to Ishikawa soon and I appreciate this post a lot!
Terrifying! Thank you for this great ressource though! Aaah! *is a bit freaked out*
Just so you get your rashes straight: as noted in prior articles dani always bit twice and usually around the ankles/wrists/wherever your pajamas end. The mind-melting itchiness of the pine processionary caterpillars of doom is similar at first, but your symptoms will include a red rash on exposed skin (in my case, my neck, upper chest, and arms); no bite-marks or visible stingers, but sort of a sunburn-hives combo. Get a doctor’s note, because your CO/landlord will have to call in the big guns. Do not attempt to clean up the caterpillars or their bodies; if your exterminator does not remove the dead bugs, wear a rainsuit, rubber boots, mask and goggles (seriously) and flush the dead ones off your porch with a bucket of water. If treated immediately, the rash will go away in 1-2 weeks.
I was bitten by a mukade while sleeping in my bed. It took a chunk out of my left knee. Hurt like crazy!!! I tried to ice the bite, but it didn’t help with the pain or swelling.
Interestingly, when my professor came to help, she said I was doing it wrong. For relief from mukade bite, apply HEAT. She explained that the toxic protein temporarily denatures above a specific temperature (that I now don’t remember). It was amazing. We used the detatachable shower head, and as long as my knee was hot, hot, hot, it wasn’t as ouch-y.
I took ibuprofen and benadryl. We called a nurse, but they just said to keep an eye on it. The swelling went down in a few days, but I had a mark for a month. My research program moved me to a different apartment, sent in an exterminator who killed the mukade, and then fumigated the whole building. Good riddance!