How to Get Rid of Cockroaches (and Keep Them Out)

The short answer

Place small gel bait dabs in cracks and crevices where roaches travel. Add sticky monitoring traps. Cut off food, water, and clutter. Seal the gaps they use to enter and move between rooms. Then wait. An effective bait program takes a week or more to work, and that is normal. UC IPM is direct: gel baits are “very effective when placed in or near locations where cockroaches harbor or forage.” The other things people reach for first - foggers, bug bombs, and repellent sprays - work against this plan.

Identify what you are dealing with

Most US homes have one of three roaches, and the species changes the strategy.

• German cockroach, about 1/2 inch long, light brown, with two dark stripes on the back of the head. The indoor species. UC IPM calls it the most common indoor roach. It lives in kitchens and bathrooms, rides in via cardboard boxes and grocery bags, and breeds indoors year-round. A single female and her offspring can produce over 30,000 roaches in a year.
• American cockroach, up to about 2 inches, reddish brown, with light-colored edges on the plate behind the head. The large outdoor-to-indoor roach. UC IPM places it in sewers, storm drains, and similar outdoor spaces, from which it forages indoors. It wanders in through drains and gaps around plumbing.
• Oriental cockroach, about 1-1/4 inches, almost black, sometimes called a “water bug.” UC IPM puts it in cool, damp places: basements, garages, and around drains.

Size and the room you saw it in usually tells you which. A small roach on the kitchen counter at night is almost certainly German. A large roach in the bathtub drain is more often American or Oriental. German roaches need a different plan because they breed inside your walls, not outside the house.

Why cockroaches are hard to eliminate

A few facts explain why a can of spray feels like it works for a day and then things get worse.

• They hide where you cannot reach. UC IPM notes roaches “hide in dark, warm areas, especially narrow spaces where surfaces touch them on both sides.” An adult German roach can squeeze into a crack about 1/16 inch wide.
• They can live a long time on almost nothing. University of Florida flags water as the limiting factor: German roaches can survive only about 12 days with food but no water.
• They breed fast. German roaches can produce several generations per year, and UC IPM puts a single female with her offspring in the tens of thousands within a year.
• Their feces attract more roaches. University of Florida notes cockroach feces contain an aggregation pheromone that draws other roaches back to the same hiding spot.

This is why a single spray of a contact killer feels productive and is not. You kill the foragers you see and the colony remains, with egg-bearing females still laying.

The method that actually works

A four-part IPM approach: bait + monitoring + sanitation + exclusion.

1. Place gel bait in cracks and crevices. Apply small dabs of gel bait along the back edge of the counter where it meets the wall, in cabinet door hinges, behind the stove, under the sink rim, and along baseboards near where you have seen roaches. UC IPM recommends gel baits placed in or near locations where cockroaches harbor or forage. Use small bait stations for German roaches and the larger ones for American roaches, per University of Florida. Refill when empty: empty stations just become new harborage.

2. Add sticky monitoring traps. Place sticky traps under the sink, beside the refrigerator, behind the stove, and inside cabinets. They tell you where the activity is so you know where to bait. Penn State Extension: traps will tell you where the hot spots are.

3. Cut off food and water. This is the step most people skip, and it is the step that makes everything else work. Store food in sealed containers. Wash dishes the same day. Wipe crumbs out of the toaster tray and the gap between the stove and the counter. Take pet food and water bowls up overnight. Fix any drip under the sink or at the fridge.

4. Seal the entry points. Caulk gaps around pipes, wires, and conduits where they come through the wall. Add door sweeps to outside doors. Use drain covers in seldom-used drains so American and Oriental roaches cannot come up through the sewer line. Pull mulch and ivy back from the foundation so outdoor roaches do not have a covered highway to the wall.

Give the bait at least a week before judging. UC IPM: “An effective bait program does not give immediate results but instead may take 7 days or longer.” If you see no improvement after 30 days, switch bait brands. Penn State flags rising bait resistance in cockroaches and recommends switching products rather than reapplying the same one.

What NOT to do

The reflex is to buy a fogger, set it off, and call it done. It does not work and it makes things worse.

• Bug bombs and total release foggers. NC State University researchers tested four commercially available bug bombs in apartments with moderate to severe German cockroach infestations and found them ineffective. The aerosol settles on exposed horizontal surfaces like floors and counters, while roaches spend almost all of their time on the undersides of surfaces and inside cabinets, exactly where the mist does not reach. UC IPM is blunt that foggers “don’t reach the crevices where cockroaches harbor and breed and can be hazardous,” a hazard it attributes to flammability and exposure concerns.
• Repellent sprays around bait. A contact or repellent spray applied near bait drives roaches away from it, so the two work against each other. If you commit to baiting, skip the repellent sprays in the same room.
• Outdoor boric acid. UC IPM does not recommend boric acid outside because it is toxic to plants. Indoors, boric acid dust in wall voids has a place, but it is supplemental to gel bait, not a replacement.

The health angle

This one is real and worth taking seriously if anyone in the home has asthma or allergies. EPA: cockroach “feces, saliva, eggs, and outer covering, or cuticles left behind on surfaces contain substances that are allergenic to humans, especially those with asthma or other respiratory conditions.” Cockroaches and their droppings can also trigger asthma attacks. EPA also notes cockroaches carry bacteria that can cause salmonella, staphylococcus, and streptococcus if deposited on food. Vacuuming cracks and crevices removes the old skins and feces that drive the allergy load.

When to call a pro

A serious infestation is past the point where a weekend of gel bait and cleaning will finish it. Call a licensed pest professional if:

• You are seeing roaches in multiple rooms, not just the kitchen.
• You are seeing roaches in daytime, which usually means the population is large and the harborages are full.
• You live in an apartment or condo and neighbors have roach problems. Roaches move between units through shared plumbing and wall voids, and one unit baiting alone rarely solves it.
• Your bait and sanitation plan has been running for 30 days with no decline. Penn State notes that cockroach resistance to consumer baits and gels is rising, and a pro can bring treatments and placements a homeowner cannot.

A pro can also identify the species, treat wall voids you cannot reach, and place tamper-resistant bait where children and pets cannot get to it.

Keep them out

After the bait program has worked, the cleanup is what stops the next wave.

• Keep the kitchen clean of crumbs and grease, especially behind the stove and under the toaster.
• Take trash out nightly and use a bin with a lid.
• Vacuum under the refrigerator and along baseboards weekly.
• Re-caulk as needed around pipes and sinks.
• Check incoming boxes and bags for German roach hitchhikers before bringing them in.

Cockroaches are not a one-time fix problem. They are a keep-the-environment-hostile problem. Cut food, cut water, cut harborage, and check the sticky traps every couple of weeks to catch a new population before it grows.