Roach Nest: What It Looks Like, Where to Find It and What to Do

TL;DR

• A roach nest is not something roaches build: it is a crack, void or spot behind an appliance where they crowd together.
• Look for droppings (coffee grounds or black pepper specks from small species like the German cockroach), small brown bean-shaped egg cases, pale shed skins and roaches of every size.
• Check warm, damp, dark spots near food and water: under sinks, behind the fridge, dishwasher and stove, and inside cabinets.
• Find it at night with a flashlight, or with sticky traps: the traps with the biggest catches are usually closest to the nest.
• Put bait right at the nest, next to the droppings, where cockroaches will find it (UC IPM), and it is usually best to leave the area alone rather than spray it.
• Need help? Get a quote from a recommended local exterminator through Pest Agent's referral form.

Finding the roach nest is the step that makes every other treatment work, and it is also where most searches go wrong. People pull the fridge away from the wall expecting something like a wasp nest or an ant hill, see nothing that looks built, and decide the roaches must live somewhere else.

The clues are usually right there: dark specks like ground pepper in the corner of a cabinet, a few brown egg cases, a pale shed skin. Bait set beside those specks does far more than spraying the baseboards at random, and the reason has to do with what a roach nest actually is.

What Is a Roach Nest?

A roach nest is a hiding spot where cockroaches crowd together, not a structure they build. They move into a crack, a void or the back of an appliance that already offers darkness, warmth and moisture, hide there together during the day and leave at night to look for food.

Do Cockroaches Build Nests?

Cockroaches do not build nests. According to the University of Kentucky, cockroaches do not live in centralized nests or colonies like ants, bees and termites. Entomologists often call these spots "harbourage", a place where insects hide and live. "Roach nest" is the everyday name for the same thing, and it points you to where treatment works best.

Why Do Cockroaches Gather in One Spot?

Cockroaches gather in one spot because their droppings carry a scent that attracts other cockroaches. The University of Kentucky explains that cockroaches congregate in response to aggregating odours in their feces, and UC IPM notes that the fecal specks contain a natural attractant, or aggregation pheromone. The nest marks itself: the more droppings build up in a crack, the more roaches it draws, which is also why a heavily spotted area is the best place for bait.

How Small Is a Roach Hiding Spot?

A roach hiding spot can be very small. UC IPM reports that an adult German cockroach can hide in a crack 1/16 inch wide (about 1.6 mm), and Penn State Extension notes that their wide, flat bodies let them slip through narrow openings with ease. Health Canada adds that cockroaches are often drawn to dark or damp areas near food, beneath and behind appliances, and to cracks, crevices and pipe openings.

What Does a Roach Nest Look Like?

A roach nest looks like a dirty crack or corner covered in dark specks, with egg cases, shed skins and roaches of every size nearby. You rarely see inside the nest, so look for the debris that builds up at its entrance.

Droppings

Droppings are the clearest sign of a cockroach nest. Small species, such as the German cockroach, leave droppings that often look like coffee grounds or specks of black pepper, according to Orkin Canada. Larger species, such as the American cockroach, leave droppings that can look like mouse droppings but slightly smaller. The thicker the spotting, the closer you are to the nest.

Smear Marks

Smear marks are dark spots or streaks left where cockroaches rest and travel. UC IPM lists them among the signs of an infestation and notes that German cockroaches can leave stains on surfaces they touch. Look for them on hinges, cabinet corners, the edges of shelves and the wall right next to a crack.

Egg Cases

Egg cases (oothecae) are small, brown, bean-shaped capsules, and finding several in one spot is a strong sign of a nest. UC IPM gives these details:

• German cockroach: light beige, usually about 1/4 inch (about 6 mm). The female carries it until it is nearly ready to hatch, and it usually holds 30 to 48 eggs, according to Penn State Extension.
• Brown-banded cockroach: light brown, usually about 1/4 inch (about 6 mm), glued to ceilings, the underside of furniture or the inside of closets, sometimes several stuck together.
• Oriental cockroach: dark red-brown, about 3/8 inch (about 1 cm), left in debris or food in sheltered spots.
• American cockroach: about 3/8 inch (about 1 cm), brown when laid and black within 1 to 2 days.

For the full list of signs, see our guide to cockroach infestation signs.

Shed Skins

Shed skins are the empty, pale outer skins young cockroaches leave behind each time they grow. UC IPM counts cast skins among the main signs of an infestation. Finding them in different sizes in the same corner means roaches are growing up there, which is exactly what a nest is. Shed skins and droppings carry allergens, so vacuum rather than sweep.

Roaches of Every Size

Roaches of every size in one spot point to a breeding nest. Young cockroaches (nymphs) look like adults but are smaller and have no wings, according to Penn State Extension. A cluster that mixes tiny nymphs, medium ones and winged adults is a breeding group, not a few strays that wandered in.

Dead Roaches

Dead roaches near a crack, under the sink or behind an appliance can mean a nest is close by. A steady supply in the same spot is a useful clue to where the living ones hide.

Musty Odour

A musty odour is a sign of a large nest. Penn State Extension notes that high cockroach populations produce a characteristic odour, and UC IPM says German cockroaches can leave unpleasant odours on surfaces they contact. If a cabinet smells stale and oily even after cleaning, check its corners and the gap behind it.

Where Do Cockroaches Nest in a House?

Cockroaches nest in warm, damp, dark spots close to food and water, which in most Canadian homes means the kitchen and the bathroom. The German cockroach, the most common indoor species, does not live outdoors, according to the University of Kentucky, and Health Canada notes it has been found in buildings as far north as Nunavut. For a room-by-room checklist of every hiding spot, read our guide on how to find cockroaches and their hiding spots.

Kitchen

The kitchen is the most common place for a roach nest. The University of Kentucky lists cracks and crevices under sinks, beneath and behind refrigerators, dishwashers and stoves, near trash containers, and inside cabinets and pantries as preferred hiding places for German cockroaches. One spot people often miss is the hollow space under the lower cabinets, behind the kick panel at floor level. For kitchen-specific tips, see how to prevent roaches in the kitchen.

Bathroom

The bathroom is the other common place for a cockroach nest, because it offers water and warmth. Check the cracks under the sink and around the toilet and the pipe openings in the wall, which Health Canada names among common hiding spots.

Inside Appliances

Appliances that stay warm can hold a roach nest inside them. The University of Kentucky notes that German cockroaches also congregate in clocks, toaster ovens and other heat-producing electronic equipment. The space beneath and behind the refrigerator, dishwasher and stove is also warm, dark and close to food and water.

Bedrooms

Bedrooms can hold a roach nest when the infestation is large or food is scarce. According to the University of Kentucky, German cockroaches move into bedrooms and closets when populations are large or food is scarce. The brown-banded cockroach is different: it nests anywhere in the home, often outside the kitchen, in the upper parts of walls and closets, behind picture frames and under or inside furniture, where it glues its egg cases to the underside of dressers and tables. Read more about cockroaches in the bedroom.

Basement

The basement is where the larger species nest. The University of Kentucky says the Oriental cockroach prefers cool, dark, damp places such as crawlspaces, cellars and basements, often living in floor drains and sump pumps. The American cockroach congregates in floor drains, sump pumps, pipe chases and laundry areas. If you see big, dark roaches near a floor drain, read our guide on how to stop cockroaches from coming up the drain.

Inside Walls

Walls can hold a roach nest in the hollow spaces behind drywall, especially around plumbing. In apartments, the University of Kentucky notes that cockroaches can travel between units through common walls, ceilings, pipes and wires. If roaches keep coming out of an outlet, a gap behind the backsplash or a pipe opening, the nest is probably in the wall void behind it.

How Do You Find a Roach Nest?

Finding a roach nest means tracing roaches and their droppings back to the tightest, darkest spot near food and water. Combine a night inspection with sticky traps to narrow it down.

Night Inspection

A night inspection with a flashlight is the fastest way to find a roach nest. Cockroaches are mostly active at night, according to Health Canada, so wait until the house has been dark for a while, then walk into the kitchen and switch on a bright flashlight. Watch where the roaches run: they head straight back to their hiding spot.

Shine the light into corners and along wall and cabinet edges, where UC IPM says cockroaches tend to gather and travel.

Following the Droppings

Following the droppings leads you to the nest. Start where you see scattered specks, then follow the spotting to where it is thickest: the back corner of a cabinet, the hinge side of a door, the gap behind the stove. The heaviest spotting is often close to the entrance of the nest.

Sticky Traps

Sticky traps show you where roaches are most active when you cannot see the nest. UC IPM suggests placing them at floor-wall junctions, in all room corners, against walls behind large appliances and inside cabinets. Number each trap, check them daily for several days, and note which ones catch the most: many roaches are caught within the first 24 hours. Penn State Extension says one week of trapping at ten or more sites usually gives enough information. The traps with the biggest catches are closest to the nest.

Inspection Mirror

An inspection mirror helps you see behind appliances and under cabinets without moving everything. UC IPM suggests a small mirror on a long handle for hard-to-see areas, combined with a flashlight to check cracks, the space under counters and the area around the water heater.

What Should You Do After Finding a Cockroach Nest?

After finding a cockroach nest, put bait right at it, in cracks and crevices where cockroaches will find it (UC IPM), and it is usually best to leave the area undisturbed rather than spray it. Roaches eat the bait, go back to the nest and die there, and the University of Kentucky notes that others can be poisoned through their droppings. For a broader action plan, see what to do if you have cockroaches.

Bait Placement at the Nest

Bait placement at the nest is the most effective thing you can do. UC IPM calls baits the primary pesticide tool for cockroaches and says to place them next to fecal specks. The University of Kentucky recommends:

• Placing bait stations flush against corners and the edges of cabinets, where roaches travel
• Using many small, pea-sized dabs of gel bait rather than a few large ones
• Baiting wherever you see fecal spotting or roaches
• Not spraying cleaners or other insecticides around the bait, which can put roaches off it

Roaches find bait while they forage rather than travelling to it, so more placements work better: the University of Kentucky notes that more than a dozen may be needed just for the cabinet under a kitchen sink. Health Canada says bait stations kill insects about 48 to 96 hours after they eat the bait, and UC IPM notes that results may take 7 days or longer to show. Choose a product with a PCP number on the label, which shows it is registered by Health Canada, and follow the label. For product options, see our roundup of the best cockroach killer.

Why Foggers Backfire

Foggers backfire on a roach nest because they do not reach it. The University of Kentucky explains that very little insecticide from a total-release fogger (bug bomb) gets into the cracks and voids where cockroaches spend their time, and that the ingredients tend to be repellent, making roaches move deeper into wall voids. UC IPM adds that sprays only give short-term knockdown and may spread roaches. Foggers can also be a fire hazard near a pilot light or other open flame.

Boric Acid Dust

Boric acid dust can reach parts of a roach nest that baits cannot, such as wall voids and the space under cabinets. In Canada, boric acid dust is now registered only for professional use: Health Canada cancelled home-use dusts, with sales ending on July 22, 2018. Homeowners can often use a registered diatomaceous earth dust instead, since Health Canada lists diatomaceous earth among the active ingredients registered in Canada. The University of Kentucky advises applying it as a fine deposit barely visible to the eye, because cockroaches avoid heavy piles of powder. Never put it on countertops or food surfaces, do not puff it into electronics, and keep it away from children, pets and food, as Penn State Extension advises.

Vacuuming the Nest

Vacuuming the nest area removes droppings, shed skins and egg cases. Health Canada suggests putting the vacuum bag in soapy water afterwards, and UC IPM recommends a vacuum with a HEPA or triple filter, because shed skins and droppings can become airborne and trigger allergies. Vacuum around the nest, not over fresh bait: let the bait do its work first, then clean up.

Sealing Cracks

Sealing cracks takes away the nest site once the roaches are under control. Health Canada recommends caulking cracks, crevices and pipe openings and covering vents, open pipes and drains with fine mesh screens. The University of Kentucky suggests caulk, foam or copper mesh around pipes and wires that pass through walls, which is especially useful in apartments. Our guide to cockroach prevention covers the rest of the house.

Removing Food and Water

Removing food and water makes the bait the easiest meal around. Health Canada recommends cleaning up spills right away, storing food in sealed plastic or glass containers, not leaving pet food out all day, taking out garbage daily, fixing leaks, insulating sweating pipes and running a dehumidifier in damp areas.

When to Call a Pest Control Professional

Calling a licensed pest control professional makes sense when you find more than one nest, when roaches are showing up in daylight, or when weeks of baiting have not reduced the numbers. If you rent, tell your landlord right away: the Government of Manitoba advises against tenants using store-bought chemicals on their own, because this can spread roaches to other units. A good professional inspects on each visit and treats the cracks and hidden areas where roaches live, not just the baseboards, according to the University of Kentucky. Learn what cockroach pest control involves, or get a quote from a recommended local exterminator through Pest Agent's referral form.