Big Roaches Big Trouble In The Bathroom

Out of all the insects pest professionals take care of a daily basis, big roaches just don’t ever seem to make it on the most difficult list. These lumbering giants don’t have near the reproductive numbers as their smaller cousins. They aren’t especially illusive and let’s face it, they kind of stick out when you open up a kitchen door or move a box in the garage.

So whenever I get a call for ‘big roaches’ I must admit. I far too often take them for granted and don’t go into the account with the mindset of a detective. I mean look for the moisture right? Kick over a pile of leaves or lift up a trash can that’s been sitting there for months and you got it licked-don’t you? Well around about my 3rd call back and I start wondering, just where are these things and why haven’t killed them?

The area of the home this happens in quite often is the bathroom & over the years most pros know where to look. So maybe this is just a reminder for some of you or perhaps a couple of these spots will be new places to look at whenever you get persistent big roach problems.

Summary Of Places To Check

The Commode; Looking at our eh hem, thrones, we might think of them as solid fixtures. In reality they are hollow and can offer our huge friends a nice place to hide in protective comfort. Check the base for gaps or missing grout where the can enter. Many times their fecal matter builds near the entry. Check the tank itself. Just pop the tank lid off and you can sometimes be very surprised. It’s not a a really well sealed lid and who wouldn’t want to live in a place with a eternal water supply?

Under The Sink; Remember that slow drip you’ve meant to take care of for a few years now? Well, slide that tupperware dish over you use to catch the drips and take a good look at your pipes as they go into the wall. Usually the hole is about 3 inches around for a 1/4 inch pipe. And don’t let those silver flanges fool you, many times there just hanging there and give you the illusion everything is sealed up but big roaches scoot in and out with ease. Also there are TWO layers of a wall back there for our roaches to hide in. One is the back of the cabinet itself and that can sit up to an inch away from the wall it’s up against. That wall is the bathroom wall and hordes of roaches can live in among the studs.

These are actually Asian roaches that plagued this homeowner even after 3 visits from a “pro.” It only took 5 minutes and the problem was solved & just who do you this is this ladies hero now? 😉

Now look at the floor of that cabinet. It’s about 4 inches higher then the floor right? There’s a false bottom under there with enough room for a moose. Now it may be sealed up as far as you can see but on the backside where the cabinet sits against the wall–it’s all open! You can also reach your hand up underneath the front lip and many times you can feel that the front face board does not go all the way up. This makes life easy for our behemoth beasts having a front & back door but also gives you a great way to access the void with a treatment.

Exhaust Fans & Recessed Lighting; These spots are too often overlooked but easily rectified as a trouble spot. Roaches fecal matter or dead bodies often betray them as you can see the build up in the lights glass or the slits of the fan. In my travels, this is the number one spot to look when you’re dealing with persistent roaches and all the spray and dust in the world hasn’t been helping. It only takes a few minutes to check and/or treat but I think the thought of running out to the truck for a ladder makes us put it off. The collar or covers usually don’t sit super tight against the ceiling so roaches squeeze out with ease. (they don’t always find their way back and that’s why I think homeowners find them just wandering about) The unit covers pull down pretty easily and if you see evidence it’s simple to treat. If nothing, well it’s one more area you can rule out.

The following video (and the one just above) cover these areas visually for you and demonstrate just how easy it is for these big roaches to “keep on coming” but also how easy it can be to treat for them. One area not covered in this article or in the video is the bath trap. This too is an often dismissed or overlooked area. The link provided will show you just how to deal with this.


About The Bug Doctor

Jerry Schappert is a certified pest control operator and Associate Certified Entomologist with over two and a half decades of experience from birds to termites and everything in between. He started as a route technician and worked his way up to commercial/national accounts representative. Always learning in his craft he is familiar with rural pest services and big city control techniques. Jerry has owned and operated a successful pest control company since 1993 in Ocala,Florida. While his knowledge and practical application has benefitted his community Jerry wanted to impart his wisdom on a broader scale to help many more. was born from that idea in 2007 and has been well received. It is the goal of this site to inform you with his keen insights and safely guide you through your pest control treatment needs.

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  • Dylan

    This is why your blog is awesome…8 years and I have never checked an exhaust fan. Thanks for the tip!

  • stuto1

    I have a newer customer who told me when she was in college she heard noise coming from a bathroom fan. She pulled off the cover and it rained roaches on her! Instant pest control user for life!

  • That would leave a lasting impression – let alone some uneasy moments when she’s, eh em, sitting down doing her business….lol

  • Don’t feel bad–my tech of 13 years looked at me dumfounded when I showed him the little phone video (the one at the top) of all those roaches in HIS CUSTOMERS vent……

  • good tips! its easy to become complacent when you get the am. roach calls.

  • Thx–that’s so true

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  • Chantel Nicole

    I have seen a big cockroach like this two time since January in my bathroom. The first time it ran under the sink. Tonight my husband killed it. He says it’s no big deal. Never before have I seen them. Is an isolated cockroach possible?

  • Jennifer Rivera Barcelo

    Whhattt !!! Omg!!!!

  • Janine Wilson

    Really appreciate your video more than I can say – I have lived in my apartment for many years and have never had the problem I have had that has been driving me crazy over the last year or so. I don’t usually see any droppings – just little tiny babies on the floor -dead because I have done a spray around most surfaces. The appearance of a big one seemed always to coincide with me using any of the taps or my washing machine that pulls cold water. That the building had work done on the cold water mains kind of alerted me to something not being right. I have included spraying around the base of the toilet and behind the cistern. Suddenly when I flush the loo I started getting dead large cockroaches coming out with the water from the cistern. It is REVOLTING. I took the cistern lid off and found a live biggie above the waterline which I despatched and then sprayed into the crevice of where the water main comes from the wall. I also followed your advise and found one little area around the base of the loo near the wall that seemed not totally sealed. Another blast. Questions I have – how long before I can expect to wipe out a colony. They are driving me insane. It is a revolting way to start each day. Secondly is there something you can post about types of cockroaches? I haven’t had these before – these ones are the ones I hate the most – the big ones with wings. Previously I had a problem with the banded ones – in Australia we sometimes call them bush cockroaches but I think they are Asian? Do those big flying ones kill the other breed? If they are getting into the cistern is there much risk they are behind the walls behind the bath, the sink and the washing machine? It is so depressing to be honest. There was a big storm about a year ago and one night suddenly had all of these horrible ones coming in through the window and I was spraying, chasing and picking up cockroaches for about 3 hours in the middle of the night, They seemed to come from the rafters outside my bathroom – so have they found comfort in my cistern or are they in the wall? Shall I keep spraying and eventually will wipe them out? I can’t live like this much longer without losing my mind!! There is no fecal matter around – just the dead babies.