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An 8-Step Guide to Eliminating & Preventing a Cockroach Infestation in Your Condo

Sure you saw something move out the corner of your eye? Felt something run over your leg in the night?

You may have cockroaches in your condo or house.

Now, I don't kill animals unnecessarily, but a cockroach invasion is a serious health hazard, especially when you have a baby in the house.

And that's the situation I was facing at the time: No matter how much I cleaned, how many I killed, they kept appearing — seemingly from nowhere.

Bear in mind that my apartment was fairly new, not more than 7 years old. So this problem doesn't just arise in older buildings, though undoubtedly the severity is likely to be greater in older buildings where roaches have had time to completely infest.

So rather than spending my life as a cockroach killer, I embarked on a mission to make my condo a natural cockroach repellent — a place where cockroaches didn't want to spend the night.

In this post I share my experience of expelling these pests from my condo and present my 7-step guide for you to do the same. This post will also come in handy for those viewing condos/houses for rent. If you know the telltale signs you can avoid moving into a roach-ridden property.

But first, a few things you should know about cockroaches in Thailand.

Cockroaches in Thailand

German cockroach and American cockroach are the two species most commonly found in Thailand. The German variety is the most likely to invade your condo, and the larger American type is the one you'll see scurrying out of a drain and across the street.

Knowing more about their habits can help you identify the most effective control methods.

american-cockroach-thailand

german-cockroach-thailand

Image Credit: Rentokil

6 Signs That You Have Cockroaches in Your Condo

  1. Roach Poo – check for black grainy droppings in cabinets and along the floor where it meets the wall.
  2. Smear marks – where water is present, you may see brown and irregular shaped smear marks on horizontal surfaces and wall floor junctions.
  3. Shed skin – evidence of brownish skins can be found close to where roaches are breeding, as young cockroaches shed skins about 5-8 times as they mature to adulthood.
  4. Egg casings – appear as small, dark brown oval-shaped casings (see the image in this post).
  5. Unpleasant odour – you may detect a distinct musty smell when cockroaches are present in large numbers. Open cabinets and kitchen cupboards and have a sniff.
  6. Getting sick regularly: If you have regular bouts of any symptoms in the graphic below, you may be getting infections from cockroaches in your home.

signs-of-a-cockroach-health-infection

The 3 Most Common Associated Health Risks

Through their poop, urine, vomit and bodies, cockroaches transmit infectious pathogens. Around 32 different species of bacteria can be found on cockroaches, and they are responsible for spreading six different parasitic worms.

This means cockroaches are a serious health risk and can may you sick.

1. Asthma

Those who suffer from asthma are at serious risk. Asthma attacks may occur after inhaling allergens released by cockroaches. The World Health Organisation estimate around 23-60% of people with Asthma are sensitive to cockroach allergens.

2. Salmonella

Cockroaches are also known to spread salmonella. The Centre for Diseases Control (CDC) estimates that salmonella causes more than 1.2 million illnesses each year in the US, with 2,3000 of those resulting in hospitalisations.

3. E.Coli

Cockroaches can transmit E.Coli (Escherichia Coli), a serious food poisoning.

cockroach health risks

How Cockroaches Adapt to Your Routine

Most species of cockroaches are active (i.e. awake) during the four hours after lights-out. The cockroaches in Thailand are especially smart and quickly adapt to your routine. For example: when you go out to work, they may come out to play. But when you return and twist that door handle,  they scurry back into their crevices.

The most likely time for activity though is when you go to bed. They wait a while for absolute silence and then come out to feed and breed.

This is how cockroaches evade being caught and seen, and why you often don't discover that they live with you until it is too late. The first time you see one might well be by accident, for example when you open a box you haven't opened for a while, or you might see a dead one in a corner of a room when you move a piece of furniture.

If you want to do some cockroach hunting, lie in bed with the lights off for an hour and then switch on a light suddenly. Or quietly go to the kitchen and switch on the light. Move around some things on shelves and the worktop and you'll no doubt see one scurry.

Be Careful When Using Sprays

Sprays in Thailand can be very harmful to your health, especially if you are inhaling the chemicals regularly. Sprays are not a good long-term solution because you will be forever spraying and, when you miss, you'll panic and spray too much and end up poisoning yourself.

If you use a spray to kill a cockroach, get as close as you can and spray one solid spray in a direct hit. Then pick up and dispose. Never use sprays around babies, children or pets.

Besides, you need to treat the root of the problem, and for every one sprayed there's 10 more lurking close by.

Why Traps in Condos Aren't Very Effective

Man, I remember one time we went away for a few weeks and I put some traps down. Never again!

We retuned to find around a ton of dead cockroaches around the traps, but it quickly became evident that the traps had simply attracted all the other cockroaches in adjacent rooms to ours. And many hadn't fallen for the trap and instead taken up residence.

Why? Well, cockroaches attract each other, so if there's loads of others in close proximity they'll just wander in. Clearly some didn't take the bait. So not only was I left with a ton of dead bodies and a whole lot of poop to clean up, I had new friends too!

Prevention is better than cure.

Why Cockroach Infestations in Thailand Are Unique

Apartments/condos are in close proximity to other, so cockroaches can easily come into your apartment, feed, drink, lay and egg and then go to another room when disturbed.

In this respect, it is unlikely that you will uncover one area in a room where there is a nest of 20 or more. The most I found was 4 in one box.

This is different to a house infestation in Europe or the US, where growth is rapid and you will usually uncover a big nest with hundreds.

What this means is that it is easy to be fooled into thinking the problem has gone once you have killed one or two. But if they have a reason to come back they will.

How Cockroaches Attract Each Other Using Poop!

You will usually see isolated instances of a single cockroach alone in the hallway of a condo block, but don't be fooled, these insects are geniuses at finding each other.

Cockroaches can communicate using their feces. Researchers studying roach aggregation behaviors found that compounds produced by bacteria in the gut of roaches help them find each other. The findings, published in Proceedings of the National Academy of Sciences, suggest that microbial communities in the gut enable communication.

So in short, you need to clean up their poo. Otherwise more and more will pay you a visit. The poo are like black breadcrumbs. The best way to identify it is to take a baby wipe and run it across a surface, like your kitchen worktop. Do this each morning to see whether there has been activity during the night.

cockroach poo

Some poop I photographed on a kitchen worktop at an office building in Bangkok

An 8-Step Guide to Eliminating Cockroaches From Your Condo

Step 1: Cover Your Drains

The first, and a super effective way to prevent cockroaches entering your home is to cover plug holes and drains.

Make a habit of putting the plug in the sink after use. The same goes for the kitchen sink and the drain in your shower.

Also cover the drain in your balcony, as outside of the rainy season water flow will be minimal and roaches can easily climb up the pipe.

In addition, tape over your overflow hole in the kitchen and bathroom sinks. Cockroaches in Thailand live in the drains and pipes. They can move between rooms this way too. If you cover up you will cut them off and they'll go elsewhere.

Step 2: Cover Your Plug Sockets

The best advice I got on how to get rid of cockroaches was from an ex pest control guy. I met him by chance at a coffee shop and he happened to mention he'd worked in the game.

I was telling him that I just couldn't fathom why every time I thought I'd eliminated the problem more would appear.

He explained that the problem wasn't me but the building. “Once they get in the walls, you've had it. The condo building needs to be emptied and treated”.

By ‘in the walls' he meant behind the walls: in lift shafts, behind plaster board, etc. The roaches can breed and hide there undisturbed and then run in and out of apartments through gaps and sockets as they please.

The problem is that a condo owner isn't likely to admit they have a problem. You'll always hear the same excuses: it's rainy season, clean your room, it's because you're cooking, put traps down, blah, blah, bah.

It just wouldn't be possible for them to move everyone out and treat the building for  3 weeks or more. And, in reality, most Thai residents accept cockroaches as part of city living. So it's only you, “the farang”, who really complains.

Anyway. The guy advised me to cover all my unused plug sockets with tape, and keep the ones I used plugged in. I use extension plugs with surge master trips so it was safe to leave sockets plugged in. This one single piece of advice cut my problem by 60 percent or more. 

I noticed an instant reduction in the amount of cockroaches I saw in a week. But just because you can't see them, doesn't mean they aren't there.

Step 3: Leave Gaps Between Furniture

Having found tons of the critters over time, I deduced that they love to hide between a gap; so between a wall and a cupboard, behind a drawer, between crevices and papers.

To combat this, I pulled all furniture away from the wall by a good couple of inches. Not only does this mean you can keep a constant check with a quick peak here and there, but the Cockroaches won't feel secure resting in these places during the day and will vacate to a more suitable environment, i.e. outside of your condo!

Similarly, don't keep piles of papers in drawers. Throw old magazines away and regularly rustle, move and dust off  books to disturb the environment. Cockroaches love rooms with areas that remain disturbed. So do everything you can to upset the environment.

Step 4: Block Gaps Under the Front & Back Doors

Condo or house, I'm willing to bet a huge part of your problem is your neighbours. Unclean kitchens, strong smells and cockroach poo all attract other cockroaches.

So if your neighbours have roaches, the likelihood is you will get visitors too.

In a condo you'll find that roaches travel down the hallways at night, nipping in and out of the rooms. Much of this is done under the door. So reduce their ability to get in by blocking the gap under the door with a draft excluder or towel. It's not foolproof but it does help. Do the same with the back door.

Step 5: Empty Bins Daily & Wipe Surfaces with Disinfectant

If you have a smelly bin and your neighbour doesn't, the cockroach will show a preference for your lace. Empty bins daily and never leave strong smelling waste hanging about for long. Certainly never leave a dirty bin in over night.

Also wipe down kitchen, bathroom and any other surfaces on a daily basis. Cockroaches don't like disinfectant, and most importantly it is the only thing capable of effectively wiping up their poop, urine and vomit, which can attract other cockroaches.

cockroach health risks

Step 6: Keep a Minimal Home

This is massive, and really changed the game for me. In a nutshell, don't have too many things. Cockroaches love cluttered homes because they have so many places to hide.

De-clutter your home and throw out what you don't need. It makes it easier for you to clean, easier to spot roaches because they will be exposed, and help towards ending the infestation.

One thing I learned on my quest is that cockroaches love boxes. Cardboard boxes like shoe boxes are a great place for them to nest and rest.

They will hide there in the day and then venture out when you sleep. At one of the many points I thought I was winning the fight, I cleaned out the top of our wardrobe and got a box down with some odds and ends in. Man, what a shock! Three adult cockroaches chilling out among the bits and bobs.

Make sure you clean regularly and disturb everything

Step 7: Hunt for Eggs!

Most people have no idea what a cockroach egg looks like, or how the sneaky buggers deposit them in your home.

Each egg contains an outer sticky substance that can be stuck to the most obscure of places. See the image below.

This image is from an egg I found when cleaning out a sideboard. At the last moment I thought, let me check the underside of one of the structural panels. Strategically placed underneath was a cockroach egg waiting to hatch. These creatures are smart. They know when to roam, where to hide and where to lay eggs to evade capture.

So when I say you need to clean out your entire condo or house, I mean strip it bare and leave no stone unturned. 

cockroach egg

cockroach egg

Close up of the same egg

Step 8: Inform & Educate Your Neighbours 

I'll be frank: You probably won't get much co-operation from your neighbours. You might if they are interested in cleanliness and good hygiene, but I found that most young Thais and the Chinese residents in my building didn't seem that bothered.

And this was the key problem. Had we worked together it would have been more effective. But if people are frying food every day and not cleaning surfaces and pans, and not emptying bins regularly, this is a recipe for disaster.

You might try putting a sign with a list of dos and don'ts for others to follow, and posting a copy under each door. The more cooperation you have, particularly on your floor, the more likely you are to eliminate the problem.

——–

I did get rid of my cockroach problem but it took me about month to do. And they did come back a few times after, but I acted quickly and, knowing from experience where they liked to hide, I was able to upset their plans.

However, I did move out in the end. I was just too paranoid about them coming back and having my child at a health risk. Moreover, the building management would not admit they had a problem which really annoyed me after a while.

It sucks though, especially when you like a place and an area and this problem persists to the point where you have to up sticks and move. Hopefully though my tips will help you tackle the problem.

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  1. That’s all really great advice for dealing with roaches - although covering the drains is not really necessary as a cockroach would never be able to get past the standing water in the P-trap. All the drains in your house have a P-trap where some water always sits in order to form an airtight seal which prevents sewer gases from getting into your home. Roaches will sometimes crawl into your sink and then down into the drain pipe as far as the P-trap but they can’t get past it, which means they also can’t get in from the other side of the P-trap. To do so would require diving down through about 4 inches of water and then back up through another 4 inches of water. So when you see a roach come crawling up out of a drain in your sink you can rest assured that he is coming out the exact same way he went in.In any case, I can’t say as I blame you for moving out of that place. After all, unless everyone in the building is fully onboard with the eradication efforts you will likely never be completely rid of the roaches. As a matter of fact, I recently observed a similar situation to yours on TV. You see, we have this TV show over here in the States called “Infested” and each week they present stories from 3 different families who battled a bad infestation of some kind (often only to loose the battle). It can be anything from spiders to scorpions to bats and naturally they’ve done quite a few with roaches. It’s a good show and quite addictive but its definitely not for the squeamish as the reenactments of these peoples situations are very detailed and realistic. In fact, every time I watch an episode I’m always kind of jumpy afterwards and for the rest of the night I frequently feel like something is crawling on me or I think that I see something run by out of the corner of my eye.Anyway, in this last episode there was one lady and her son who moved into a new apartment only to very quickly discover that they had a serious roach problem. No matter what they did though the roaches just kept coming back in force. Eventually they even had roaches getting inside of their refrigerator compartment (I didn’t know this was even possible) and according to one expert when this happens it means you probably have an infestation of 10,000 or more roaches. Unfortunately there was one tenant in the building who would not allow the landlord to do anything about the roaches in his unit (probably the original source of the problem) so the roaches just kept coming back and the lady finally decided she would just have to move out.Fortunately I have never had even the slightest cockroach problem myself at any of the places I’ve lived in Thailand. Part of the reason for this is that I’m a very neat and tidy person and I prefer very minimalist surroundings - although I’m sure luck also plays a part. Still when I moved into my first condo in Thailand I remember I was quite concerned about the huge gap under the front door thinking that roaches might get in this way. In the States there is always a threshold installed which takes up most of this gap, and then there is a rubber seal on the bottom of the door which mates up perfectly with the threshold when the door is closed. This not only saves energy but it also keeps any roaches or other creepy crawlies from entering your house or apartment by crawling under the front door. But despite this gap I never saw a single roach in this condo.I was actually completely expecting to see roaches at my house in Phuket because both of the bathrooms had showers that opened up on one side into a small walled off outdoor garden. I really love these types of modern open-air bathrooms, but the downside of course is that pretty much anything can crawl or slither its way into your house at night. And we did have a few uninvited guests that would hang out on the wall near the vanity mirror every night. One of these “guests” was a small tree frog, which I didn’t really mind at all. The other two were humongous spiders, which completely unnerved me. I actually don’t mind most spiders and in fact I have no problem at all letting a tarantula crawl up my arm. But there is just something about very large super fast moving spiders that totally freaks me out. These things were nearly as big as a tarantula but they could move faster than any insect, rodent, or lizard I had ever seen. Oddly enough my girlfriend claimed to have no problem at all with the spiders but she was so bothered by the cute little tree frog that she actually started using the guest bathroom for a while – go figure. Anyway we saw all kinds of creatures in and around that house but I don’t think we ever saw a single cockroach.By the way, one thing I have to admit that I like about Thai houses is the fact that they often have solid masonry walls rather than the hollow insulation filled walls we have here in the States. And this of course means no hollow spaces in the walls for insects to live and breed. At first glance these houses look exactly the same as American houses, with stucco on the exterior and plaster on the inside. But upon closer inspection you can sometimes find that there is a solid masonry core (often brick) and then the plaster and stucco is slathered on top of this to make it look nicer. This makes perfect sense in a tropical climate where insulation is not really required and where the masonry will help keep the structure cool during the day.As for condos in Thailand they are usually concrete and steel construction, but the walls separating the individual units could be made of just about anything since they are not load bearing, although I imagine that they are probably pretty much always hollow. Also the ceilings in these places are often hanging ceilings (even when it doesn’t look like it) and there is about a 16-inch space between this and the concrete floor above it – a perfect place for roaches to live and breed. Also there are utility shafts for plumbing and electrical which run through each apartment from the ground floor all the way up to the top floor, and if these are not sealed off well from the units they are a great way for roaches to get from floor to floor and apartment to apartment. And this is why it’s pretty much a loosing battle to try and completely get rid of roaches in a large apartment building. It’s better just to move out.If you live in a detached unit and have an infestation though the steps that TTL laid out should definitely solve the problem. I will say though that if you need to use poison bait (they eat the poison and then spread it others before they die) make sure to use it according to the instruction. I remember when I was in Japan I had to live in this old boarding house with a bunch of other foreigners for a while until I could get my own apartment and we had a pretty bad roach problem in that place. So, one day I come home to find that one of the girls, Nadia, had set about ten of these roach bait stations up on the countertop surrounding the gas burners. I then told her that they would be more effective if the were placed strategically in corners on the floor and in the backs of the cabinets because that’s where the roaches spend most of there time. To this she replied that she “didn’t care about the ones in the cabinets”, she only cared about the ones on the countertops – as if there were two distinct tribes of roaches, the counter top dwellers and cabinet dwellers. I tried to explain to her that they are all the same roaches but that they just spend 95% of their time in hidden places, and since these poison baits are not roach “repellant” it makes no sense to place them based on where she least wants to see the roaches. Unfortunately this logic fell on deaf ears however and being the total nut-job that she is she refused to move all the highly toxic bait from where we prepare all our meals.Also I should point out that if you don’t have an actual infestation but your are suddenly seeing adult cockroaches in your home, glue traps are the best way to track down where they are coming from. I had to do this recently when one day I just suddenly started seeing large roaches in my home for the first time ever. And I was seeing several new ones every night. I knew that they could not be living in my house and were just sneaking in from outside so I set up glue traps both outside and inside my place and from this I quickly learned that the walkway in front of my place basically becomes a cockroach superhighway at night during the summer. I also discovered that the seal under my front door was not sealing properly so some of these roaches were sneaking in under the door every night. So, I fixed the seal and now I am roach free once more. Glue traps will never eliminate an infestation of course but in addition to highlighting the traffic patterns of roaches they are also a good way to insure that other methods have actually eliminated all your roaches. For example, if the traps stay clear for several weeks then you know the roaches are all gone.
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    • Interesting on the P-trap; I knew nothing about this system. So basically any roaches you see coming up, or inside a sink or drain have entered the same way. So all that time I spent blocking the drains was fruitless :)
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      • Well actually if the contractor failed to follow building codes and did not place a properly sized vent pipe within 6 feet of the traps then it is possible in some situations for the trap water to get sucked out. In this case however you would almost certainly notice a very bad smell in your place - that is, until you ran a little water to fill the trap back up.Back to roaches though, last time I forgot to mention one the roaches’ favorite hiding places, and this is behind kitchen cabinets. When the base cabinets are installed and leveled up there is usually a gap of 2 to 6mm or more between the wall and the back of the cabinets (if they have a backboard) and this is an ideal home for roaches because they feel most secure in just these types of tight spaces. And of course the only way you can get back there to clean up all the roach eggs and droppings (or even to spray insecticide) is to completely remove the cabinets - easier said than done. This is why when I built the kitchen cabinets for my new place a few years ago I made them without backer boards. First of all a backboard is not at all structurally necessary since the cabinets will be attached to the wall. And of course the wall itself serves perfect well as a cabinet back. My upper cabinets have a backboards but I made them in a way that the backs lay so flat against the wall that not even a human hair could be squeezed between them and the wall. Roaches can still get underneath the base cabinets of course if you don’t seal the bottom edges off very well with caulk during the installation but this is never as much of a problem as the space behind the cabinets. I have never actually had any roaches living in my current place, which I built myself, but I just hate them so much that I am always thinking ahead when it comes to the construction of a place. I’m always thinking about where they could possibly get in and where they might be able to hide once inside.By the way, I noticed that after you changed the layout of the comments page that I no longer get notified of follow up posts, even when I check the box.
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  2. Wow. You have no idea how much I needed this. I've been suffering from cockroaches in my studio room for about 2 months. I first noticed them when I came in very late one night and went to make something to eat. There were two on the kitchen worktop. The thing is they are so fast! You warn against sprays but this is the only way I can catch them. Is there one spray that is safer than the others?
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    • Hey Whitey, if you live alone without pets and children a cockroach spray is okay to use in small amounts. Get as close as you can and fire one spray. Don't freak out and spray loads as you'll end up inhaling all the toxic ingredients. The safest spray is the Johnson brand that comes in a green bottle.
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      • Hey, I do not know whether this thread is still active, but regarding the spray. I use soap and bicarbonate diluted in water to spray on the roach when I detect one. It is as effective as the sprays sold in stores. You spray one to three times, it will walk a bit further, but slowly, until it cannot walk anymore and turns on its back. Cockroaches hate anything that comes close to soap. I just managed a roach problem at my condo in Singapore, and I now only use a pet/child friendly anti-roach spray (with a picture of a child holding a cat on the front) to "seal off" some possible entrances.
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      • Love reading this- been trying to combat cockroaches in my house in Thailand in months- so disgusting. Anyway, cockroaches will die if you spray them with soapy water just as quickly as with a toxic insecticide spray. I just put a little laundry detergent and water in a spray bottle. I douse them and they die within about a minute, I just have to angle the spray so the force of it pushes them away from the cupboards so they don't crawl under something and die as they are trying to escape. They breathe through their skin and the soap clogs it so they can't.... I had my landlord clean the grease trap in front of my kitchen and spray it with insecticide, I hope that helps. I don't know the status of my pea trap, there has always been a bad smell under my sink since we moved in, I'll be super grossed out if it is cockroaches. I am super clean. Any advice about what to clean the drains with to make them unattractive to cockroaches? I just feel like that's where they are coming from,- from behind the kitchen sink and under the sink cabinet or from behind the fridge- but I can't really move it... Also, diatamaceous earth is a powder available at plant stores/ nurseries in the U.S. It works great on them and fleas and ants- it's completely non toxic to animals and humans to eat or touch (don't breathe it in). It dries out insects' exoskeletons. So I spread that in the edges and corners of the under the sink cabinet... I too get afraid traps just attract more roaches, that's why I put one outside my kitchen window but I think the gardener threw it away.... Any other hints? I am too scared to turn off the lights and hunt them at night. I keep my pantry light on all night because I am so scared of them.
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        • If you live in a house then you'll always have the odd one wandering in, particularly if you live in close proximity to other houses, but still because houses are at ground level. My tips are to remove clutter, eliminate boxes and piles of clothes as best as possible. Disturb everything as often as possible and keep everything squeaky clean. Put drain blockers on drains and covers on sink holes, and keep doing what you're doing. You have a better chance of solving the issue than if you were living in a condo block. Once they take hold in a condo block it's game over. They are literally in the walls.
          Reply

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