What Attracts Roaches, and Why You Have Them Now
Roaches are attracted to water, warm hiding places and food, with water the one they can least do without, and the species decides why they are in your home. Small German cockroaches usually arrive in grocery bags, cardboard or furniture, or from a neighbouring apartment, and stay because of moisture and crevices near the kitchen. Large American and smokybrown cockroaches live outdoors or in sewers and wander in looking for moisture. A clean house can still get roaches: extension entomologists say so plainly.
Most advice on this question lists “food, water and shelter” and stops. That is true but not very useful, because the reason you have roaches, and what will stop them, depends on which roach it is. The first job is to look at the size of the insect you saw. Our cockroach identification guide covers the five species found in most US homes; this article explains what draws each of them in.
What does it mean if you see cockroaches in your house?
It depends on the size. A small roach in the kitchen usually means a breeding population indoors; a large one in the bathroom or garage is often a visitor from outside.
| German cockroach (indoor) | American, smokybrown and other large roaches (outdoor) | |
|---|---|---|
| Adult size | About 1/2 to 5/8 in (13 to 16 mm) | About 1 to 2 in (25 to 51 mm) |
| Where it lives | Only indoors; Kentucky says it does not occur outdoors | Sewers, drains, tree holes, mulch, leaf litter, woodpiles |
| How it gets in | Carried in: grocery bags, beverage cartons, cardboard, furniture, suitcases, or from a neighbouring apartment | Walks or flies in: drains, gaps under doors, vents, utility openings, attics |
| What keeps it there | Warmth, moisture and crevices near food in kitchens and bathrooms | Usually nothing; outdoor species survive poorly indoors |
| What a sighting means | A breeding population is very likely nearby | Often a single wanderer, especially in dry spells |
| Fix | Bait in harbourage, sanitation, often a professional | Exclusion, drain traps, moisture and mulch management |
Sizes are from Penn State and UF/IFAS Extension. The University of Kentucky (Entfact 614) states the German cockroach thrives in the presence of humans but does not occur outdoors, while UF/IFAS (ENY-214) notes that outdoor cockroaches do not survive well indoors and that people often overreact to them.
Water matters more than crumbs
UF/IFAS puts it in one sentence: water is the most important factor in cockroach survival. German cockroaches can survive only 12 days with food but no water, and about 42 days with water but no food. A New Mexico Department of Health guide gives the same 42 day figure and adds that German cockroaches live roughly two weeks with neither.
That is why cockroaches cluster where pipes, drips and warmth meet: under the kitchen sink, behind the dishwasher, under the refrigerator and around the toilet. Food is easy for them to find, since roaches eat all human foods plus soap, toothpaste, glue, hair and filth, according to Kentucky. Water and a warm crack to hide in are scarcer, and that is what you can actually take away.
Moisture also explains many sudden arrivals of large roaches. UF/IFAS and the New Mexico guide both note that cockroaches often come indoors during droughts, looking for moisture.
What attracts roaches to each other: their own droppings
Cockroaches do not build nests, but they do gather. Kentucky explains that they congregate in response to aggregating odours in their faeces, which appear as pepper-like specks where roaches rest. Research at NC State by Wada-Katsumata and colleagues (PNAS, 2015) found that German cockroach faeces emit volatile carboxylic acids that cause aggregation, that gut bacteria produce them, and that droppings from bacteria-free cockroaches were relatively unattractive.
The practical consequence is in UF/IFAS guidance: scrubbing faecal spotting with hot, soapy water reduces the aggregation pheromone that draws cockroaches to an area. Vacuuming also removes shed skins and droppings, which are allergens. Our article on cockroach allergens and asthma explains why that matters for children in particular.
Why you have them now
German cockroaches: something came in
UF/IFAS says German cockroaches can first infest a home when infested grocery bags are brought inside, and that they breed prolifically in corrugated cardboard. Kentucky adds beverage cartons and furniture; Penn State adds suitcases. UF/IFAS and the New Mexico guide both note that children can carry them home from school in book bags and lunch containers.
In apartments, the source may be next door. UF/IFAS describes infestations migrating between apartments through plumbing in a common wall, infesting a “clean” dwelling. If your neighbours have treated recently, roaches moving away from the treatment are a plausible explanation; our analysis of roaches and mice in New York apartments shows how common building-wide problems are.
Large roaches: the weather or the drains changed
Texas A&M describes American cockroaches moving through sewer pipes and entering kitchens and bathrooms through drains. The New Mexico guide warns they often come up through dry drain traps, and advises running water in spare bathrooms, utility tubs and toilets to keep traps full. The LSU AgCenter notes American cockroaches cannot tolerate freezing temperatures, and describes smokybrown cockroaches as losing moisture more quickly than other roaches, living in mulch, tree holes, attics and wall voids, and being attracted to light, entering structures through cracks at night.
Many people call these large outdoor species palmetto bugs or water bugs. Our guide to palmetto bugs sorts out which insect each name refers to.
Room by room: what is drawing them in
| Room | Usual species | What attracts them | Check and fix |
|---|---|---|---|
| Kitchen | German | Leaks under the sink, fridge drip pans, grease behind the stove, garbage, unwashed dishes overnight | Fix drips; empty drip pans; clean behind appliances; lidded bin; no dishes left overnight |
| Bathroom | German; American or oriental at drains | Moisture around toilets and sinks; dry floor drains | Repair leaks; keep drain traps filled; screen floor drains |
| Bedroom | German (heavy infestations), brownbanded | Overflow when populations are large or food is scarce; brownbanded favour high places and furniture | Remove food from bedrooms; inspect furniture undersides; treat the kitchen source |
| Basement and laundry | American, oriental | Floor drains, sump pumps, damp and cool conditions | Dehumidify; fill or screen drains; seal pipe gaps |
| Garage and attic | Smokybrown, American | Moisture from roof leaks, stored cardboard, firewood | Fix roof leaks; store items in sealed plastic; screen vents |
| Outside walls | Smokybrown, American, wood roaches | Mulch, leaf litter, woodpiles, tree holes, porch lights | Thin mulch near walls; move woodpiles; door sweeps; caulk gaps |
Kentucky lists sinks, toilets, the backs of refrigerators, dishwashers and stoves, trash containers and cabinets as preferred German cockroach hiding places, plus clocks and toaster ovens, and says they appear in bedrooms and closets when populations are large or food is scarce. UF/IFAS says the highest concentration of cockroaches in a home is usually around the garbage can and refrigerator. For night-time sightings at the sink specifically, see bugs in the kitchen sink.
When people record cockroaches
The Pest Control Brief analysis of iNaturalist research-grade records, pulled October 2026, shows the two main species on different calendars. American cockroach records sit at an index of 61 to 62 in May and June and climb to 134 in September, 136 in October and 155 in November. German cockroach records are highest in November, December and January (184, 176 and 171) and lowest in May (36).
The German cockroach pattern needs care. It lives indoors all year, so the winter rise most likely reflects people noticing and photographing it more when little else is about outdoors, not more breeding. These records show when and where people photographed cockroaches, mostly outdoors, not infestation rates.
The state picture shows the same split. In our Texas, Florida and Pennsylvania records, the outdoor species dominate because that is where people meet them, while German cockroaches, the species that actually infests kitchens, appear at most a few hundred times in each state.
What does not attract roaches, and what does not keep them out
- Baits do not lure roaches across the house. Kentucky says cockroaches are not drawn to baits from long distances; they come upon them while foraging. That is why many small placements in the right cracks beat a few in the open.
- Scents are a lab result, not a home defence. In a T-tube olfactometer study (Yoon and colleagues, Journal of Pesticide Science, 2009), five of 17 essential oils repelled German cockroaches at 70.0 to 96.7 per cent, four of them citrus oils, with limonene the main active component. No extension service recommends a scent to keep an infestation out of a home.
- Foggers. Kentucky says total-release foggers seldom work, scatter roaches deeper into walls, and have caused fires. Our comparison of cockroach bait versus spray covers the evidence on what does work.
How do I get rid of roaches in my house?
A few large roaches after a dry spell are usually a DIY problem: seal the gap, fill the drain trap, thin the mulch and remove the roach. German cockroaches are different. Kentucky notes a single mated female can produce thousands of offspring in less than a year, and extension sources agree that insecticides are usually needed once an infestation is established. Our guide to German cockroach treatment explains why some baits fail, and cockroach exterminator cost shows what a professional programme usually costs.
How can I get rid of roaches fast?
There is no instant fix for an infestation, but baits placed in the right cracks work quickly. Kentucky says a roach that eats bait typically dies within 1 to 3 days, and a substantial reduction overall should be apparent within a few weeks. Put many small placements where you see droppings or roaches, flush with corners and edges, keep cleaning sprays away from them, follow the label, and do not use foggers.
Frequently asked questions
Why am I getting roaches in a clean house?
Because cleanliness does not stop the routes roaches use. The University of Kentucky says that while roaches usually thrive where sanitation is poor, even clean homes can become infested. German cockroaches arrive in grocery bags, cardboard and furniture or move through plumbing from neighbouring apartments, and large outdoor roaches wander in through drains and gaps, especially in dry weather when they are looking for moisture.
What are cockroaches most attracted to?
Water and warm, tight hiding places close to food. UF/IFAS calls water the most important factor in cockroach survival: German cockroaches last only 12 days with food but no water. They also gather where other cockroaches have been, drawn by an aggregation pheromone in their droppings, which is why scrubbing away faecal specks with hot, soapy water is part of the extension advice.
What smells keep roaches away?
None reliably keeps them out of a home. In a laboratory olfactometer study published in 2009, grapefruit, lemon, lime and orange oils repelled German cockroaches, with limonene doing most of the work. That shows roaches avoid some odours in a tube, not that a scent will clear a kitchen. Extension services rely on removing water, food and harbourage, sealing gaps and using bait instead.
What is a cockroaches’ biggest weakness?
Water. UF/IFAS reports German cockroaches survive only 12 days without water even when food is available, compared with about 42 days on water alone. Smokybrown cockroaches lose moisture more quickly than other roaches, according to the LSU AgCenter. Fixing leaks, emptying drip pans and keeping sinks dry removes the resource they can least do without.
Why should you never kill a roach?
There is no good reason not to. The idea that killing one releases a smell that attracts others is not what the research shows: the aggregation pheromone is in cockroach droppings, not released by a dead roach. Clean up the body, since UF/IFAS lists cockroach body parts among the allergens. One German cockroach usually means more nearby, so killing it is the start, not the solution.
Sources
- University of Kentucky Entomology, Entfact 614: Cockroach Elimination in Homes and Apartments, Michael F. Potter.
- UF/IFAS Extension, ENY-214: Cockroaches and Their Management, Koehler, Bayer and Branscome, revised 2022, reviewed 2025.
- Penn State Extension, German Cockroaches, Steve Jacobs.
- Texas A&M AgriLife Urban Entomology, American Cockroach and Smoky-brown Cockroach.
- LSU AgCenter, Peridomestic Cockroaches Part 1, Ashbrook, Huval, Carlton and Reagan.
- New Mexico Department of Health, Cockroaches guide.
- Wada-Katsumata and colleagues, Gut bacteria mediate aggregation in the German cockroach, Proceedings of the National Academy of Sciences, 2015.
- Yoon and colleagues, Repellent activity of citrus oils against the cockroaches Blattella germanica, Periplaneta americana and P. fuliginosa, Journal of Pesticide Science 34(2), 2009.
- The Pest Control Brief analysis of iNaturalist research-grade records, pulled October 2026.
