The best way to keep cockroaches out of your house is to make it hard for them to get in, hard for them to find food and water, and hard for them to hide, then catch any newcomers early with traps and bait. That sounds obvious, but the details matter, and so does the type of roach. A small German cockroach that rode in on a grocery bag needs a different response than a big palmetto bug that walked in under the door after a storm. This guide covers the prevention steps Texas A&M and North Carolina's agriculture department recommend, why clean homes still get roaches, what doesn't work, and how to keep roaches from coming back in apartments and Southern houses.
To prevent cockroaches: seal cracks 1/8 inch or wider around the foundation, pipes, doors and windows; cover floor drains; store food and pet food sealed; fix leaks; clear out cardboard and clutter; and check boxes and bags before bringing them inside. Use bait, not spray, for any roaches that get in, and monitor with sticky traps.
Be realistic: Texas A&M says cleanliness "WILL NOT ALWAYS prevent invasions from outside sources." In the South, outdoor roaches will wander in sometimes. The goal is to stop them from settling and breeding.
First, Know Which Roach You're Keeping Out
Clemson Extension says South Carolina has more than 15 kinds of cockroaches, but only a few come into houses, and they get in different ways:
| Roach | How it gets in | What prevention focuses on |
|---|---|---|
| German cockroach (small, tan, two stripes) | Carried in on grocery bags, boxes, used furniture and appliances, or from a neighboring apartment. Lives indoors | Inspecting what comes in, food, water, clutter, and bait at the first sighting |
| American cockroach (the big "palmetto bug," up to 2 inches) | Walks in from sewers, drains, crawl spaces and the yard. The University of Florida says they wander in for food and water, to escape extreme weather, and after heavy rain | Sealing gaps, door sweeps, drains, and yard clutter |
| Smokybrown cockroach (dark, shiny, flies) | Lives outdoors around trees and mulch, and in eaves and porch ceilings. Clemson notes it may fly on warm evenings | Trimming limbs and mulch back from the house, sealing eaves and vents |
| Brownbanded cockroach (small, two light bands) | Carried in, and hides up high, in cabinets and inside electronics | Inspecting furniture and electronics, bait in high spots |
In Virginia, the most common cockroach is actually the wood cockroach, which Virginia Tech says isn't a household pest: males wander in during late spring and die off without breeding. For help with identification, see German cockroaches vs. palmetto bugs.
Why Clean Homes Still Get Roaches
Clemson Extension puts it plainly: "cockroaches can be found anywhere, not only in unclean places." A popular Quora question captures the frustration: "I try to keep a very clean place and I don't know where they come from." On Reddit's r/malelivingspace, the top answer (184 upvotes, via Google search excerpts) began: "If you're in Florida, it's impossible. I had a brand new house, wife is an absolute clean…"
Cleaning helps, but roaches are scavengers. A YouTube commenter put it well: "you can clean every molecule of edible food and the roaches will still survive because they can eat stuff like hair, cardboard." Outdoor species come in for water and shelter as much as food, especially after heavy rain or during heat. So prevention is about blocking entry and removing water and hiding places, not just wiping counters.
How to Keep Cockroaches Out: 8 Steps
1. Seal the ways in
Texas A&M says to seal any cracks of 1/8 inch or more in the foundation and exterior walls, and to check the caulking around the air conditioning unit, windows, doors and pipes. Inside, seal openings around plumbing under sinks, around furnace flues and electrical outlets, and along baseboards and ceiling moldings. Make door thresholds as tight as possible and add door sweeps, since big roaches walk in under doors. Clemson suggests steel wool as a filler for larger gaps around pipes.
2. Cover drains
North Carolina's agriculture department recommends screens over floor drains, vents and ducts, calling them "cockroach highways." American cockroaches live in sewers and come up through plumbing. One YouTube commenter who kept finding roaches in the bathtub started covering the tub drain with a rubber plug when it wasn't in use, and others suggested mesh strainers. Run water in drains you rarely use, like a guest shower or basement floor drain, so the trap stays full of water.
3. Cut off food
- Store food in tightly sealed containers or the refrigerator, NC Agriculture says, and never leave dirty dishes out overnight.
- Store dry pet food in tight containers and don't leave uneaten pet food in the bowl overnight, Texas A&M advises.
- Use a trash can with a tight lid, empty it often, and don't keep it under the sink, NC Agriculture recommends. Rinse cans and bottles before recycling them.
- Clean under and behind the stove, refrigerator and cabinets, where crumbs collect out of sight.
4. Remove water
Fix leaky faucets, drains and pipes, both groups say. Wipe sinks and tubs dry at night, don't leave water in pet bowls overnight if roaches are a problem, and check under sinks for slow leaks and damp cabinet floors.
5. Get rid of cardboard and clutter
NC Agriculture says to throw out or recycle old newspapers and paper bags frequently. Texas A&M notes that paper, cardboard, lumber, firewood and other debris next to the house give several cockroach species shelter. Store items in plastic bins with lids instead of cardboard boxes, especially in garages, basements and closets.
6. Check what you bring inside
This is the main way German cockroaches arrive. NC Agriculture says to inspect all baskets, bags and boxes of food brought into the house, and Clemson names grocery bags and boxes as common carriers. Be especially careful with used furniture, appliances and electronics, where brownbanded cockroaches like to glue their egg cases.
7. Fix the outside
Keep garbage cans clean and away from doors, stack firewood away from the house, and clear leaves and trash near the foundation. For smokybrown cockroaches, research in the Journal of Economic Entomology found that clearing a 1-foot strip around the house and trimming tree limbs 1 foot back from the roof, combined with treatment, worked better than a perimeter spray alone.
8. Watch for early arrivals
Sticky traps don't stop an infestation, but they show you where roaches are and whether there are more than you think. Texas A&M suggests placing them against walls and in corners where roaches travel, and moving any trap that catches nothing after two or three nights. Good spots: under the sink, beside the stove and refrigerator, and behind the toilet.
You've Seen One Roach. Now What?
- A big roach once in a while, especially after rain: usually an American or smokybrown cockroach wandering in from outside. Check door sweeps, drains and gaps near where you saw it.
- A small tan roach, or any roach in the daytime: likely German cockroaches breeding inside. Act right away with bait.
- Roaches in an apartment: they may be coming from the next unit. A top Reddit r/lifehacks answer put it simply: "The other units need to do everything you are doing."
Use Bait, Not Spray
When roaches get in, bait is the most effective tool for most homes. NC Agriculture calls baits low-risk and notes they get carried into walls and hiding places. It also warns: "do not use a spray in the same area since the spray may repel the cockroaches and prevent the bait from doing its job."
The research backs this up. An NC State study in apartments found that more than 62% of German cockroaches survived fogger treatments, while gel baits cut populations by 70% to 93% within a month. German cockroaches in that study were also more than 200 times resistant to a common spray ingredient. Rutgers researchers who studied whole apartment buildings found that treating every unit together, mainly with gel bait, cut the number of infested apartments by about 75% in a year. A pest professional on Reddit's r/Apartmentliving said a tube of a quality gel bait "is often all you really need."
Two tips: place small dots of gel bait in cracks near where roaches hide, not out in the open, and keep checking and re-baiting. Eggs keep hatching after the adults die, so plan on a follow-up. One YouTube commenter advised following up "at least 30-50 days later." If roaches stop eating a bait, switch to a different brand, since some German cockroaches have evolved to avoid the sugars in certain baits.
A light dusting of boric acid, labeled for cockroaches, behind and under appliances and sinks is another low-risk option NC Agriculture mentions. Use it as the label directs, and keep it away from children and pets.
What Doesn't Work
- Bug bombs and foggers: they failed in the NC State apartment study, and they can scatter roaches deeper into walls and into neighbors' units.
- Spraying where you've placed bait: the spray repels roaches from the bait.
- Lemon juice, bay leaves, peppermint and other scents: we haven't found good evidence that they keep roaches away. Some may repel briefly, but they don't stop roaches from living in your walls.
- "Borax dries out their gills": a popular claim in YouTube comments, but cockroaches don't have gills. They breathe through small openings along the body. Borate baits work because roaches eat them.
- Bleach: it can kill a roach you soak with it, but it isn't a repellent or a prevention tool. See does bleach kill roaches?
- "Stronger is better": NC Agriculture warns against mixing pesticides stronger than the label says. It doesn't work better and can hurt people and pets.
After the Roaches Are Gone
Keep cleaning. Virginia Tech notes that cockroach allergens "will persist even after the cockroaches are gone." Clemson says the most serious health problem cockroaches cause is allergic reactions to their shed skins and droppings, which matters most for children with asthma. One parent commenting under a cockroach video wrote that their 2-year-old is allergic to German cockroaches. Vacuum and wash surfaces where roaches were active.
For more on the health side, see are cockroaches a health hazard? For big outdoor roaches, see how to get rid of palmetto bugs, and for summer invasions, see why roaches come inside in summer.
When to Call a Professional
Call a pro if you see German cockroaches regularly, see roaches in the daytime, live in an apartment where neighbors have roaches, or have tried baiting for a month without results. In North Carolina, NC Agriculture advises asking to see the technician's ID card; every pest control employee there must be registered or certified. Our cockroach control service uses baits and targeted treatments across South Carolina, North Carolina and Virginia, and for a heavy problem see how to get rid of a heavy roach infestation.
Key Takeaways
- Seal cracks 1/8 inch or wider, add door sweeps, and cover floor drains.
- Cut off food and water: sealed food, no pet food or dishes out overnight, lidded trash not under the sink, fixed leaks.
- Swap cardboard for plastic bins, and check bags, boxes and used items before they come in.
- Clean homes still get roaches. Prevention is about entry, water and hiding places.
- Use bait, not spray or foggers, and follow up for a month or more as eggs hatch.
- Monitor with sticky traps so you catch new arrivals before they breed.
Frequently Asked Questions
Seal cracks 1/8 inch or wider around the foundation, pipes, doors and windows, add door sweeps, and cover floor drains. Store food and pet food sealed, fix leaks, keep trash lidded, replace cardboard boxes with plastic bins, and check bags and boxes before bringing them in. Use bait, not spray, if roaches appear.
Clemson Extension says cockroaches can be found anywhere, not only in unclean places. Outdoor roaches come in for water and shelter, especially after rain or in heat, and German cockroaches ride in on grocery bags, boxes and used furniture. Roaches can also live on crumbs, hair and cardboard you can't see.
Nothing keeps every roach away forever, especially in the South. What works long term is blocking entry, removing water and food, clearing clutter, and catching new arrivals early with sticky traps and bait so they never get a chance to breed.
We haven't found good evidence that smells such as lemon, bay leaves or peppermint keep roaches away. Some scents may repel roaches briefly, but they don't stop roaches already living in walls. Sealing, sanitation and bait are what extension services recommend.
No. An NC State study found more than 62% of German cockroaches survived fogger treatments in apartments, while gel baits cut populations by 70% to 93% in a month. Foggers can also scatter roaches deeper into walls and into neighboring units.
Yes. American cockroaches live in sewers and can travel through plumbing. NC Agriculture recommends screens over floor drains. Keep rarely used drains filled with water, and use a drain plug or mesh strainer if roaches keep appearing in a tub or sink.
Do all the usual steps, sealing gaps around pipes and outlets, keeping food sealed and using bait, but also tell management, because roaches move between units. Studies of apartment buildings show treating every unit together works far better than treating one apartment at a time.
Use bait. NC Agriculture says not to spray where you've placed bait because the spray can repel roaches from it. Gel bait in cracks near where roaches hide is the most effective option for most homes, with sticky traps to monitor.
They can, because eggs keep hatching after the adults die and new roaches can come in from outside or next door. Keep bait out and recheck for several weeks after treatment, and keep up sealing and sanitation so new arrivals don't settle in.
Sources: Texas A&M Urban and Structural Entomology Program, "Cockroach Prevention"; NCDA&CS Structural Pest Control and Pesticides Division, "Cockroach Control and Prevention"; Clemson Cooperative Extension HGIC 2449, "Cockroach (Roach) Control"; University of Florida IFAS, "American Cockroach" (EENY-141); Virginia Cooperative Extension, ENTO-528NP and ENTO-426 (wood cockroach); Z. C. DeVries et al., "Pervasive Resistance to Pyrethroids in German Cockroaches Related to Lack of Efficacy of Total Release Foggers," Journal of Economic Entomology 112(5) (2019); C. Wang et al., building-wide cockroach IPM in high-rise apartments, Journal of Integrated Pest Management 10 (2019); A. Wada-Katsumata, J. Silverman & C. Schal, "Changes in taste neurons support the emergence of an adaptive behavior in cockroaches," Science 340 (2013); M. Smith et al., smokybrown cockroach management, Journal of Economic Entomology 88 (1995); Reddit r/malelivingspace, r/lifehacks and r/Apartmentliving (via Google search excerpts); Quora (via Google search excerpts); YouTube comments under cockroach control videos.
Photo credits: Clemson University, USDA Cooperative Extension Slide Series, Bugwood.org, CC BY 3.0 US; CDC Public Health Image Library, public domain; via Wikimedia Commons.