Cockroach Infestation: Signs to Look For, Where to Check and What to Do

What Is a Cockroach Infestation?

A cockroach infestation is a population of cockroaches breeding inside your home, hidden in warm, damp spots close to food and water. According to Health Canada, cockroaches live anywhere food, water and shelter are available, and they are drawn to kitchens, bathrooms, basements and plumbing areas. An infestation can go unnoticed for some time, since cockroaches are most active at night.

A single cockroach is not always an infestation, but it is often the first visible sign of one. Our guide on how many cockroaches make an infestation explains how to read one sighting.

How Does a Cockroach Infestation Start?

A cockroach infestation usually starts with a few roaches or a single egg case carried into your home. Health Canada lists used furniture, food items, empty beer and soft drink bottles and shipping cartons as common ways they arrive. In apartment buildings, they can also spread from one unit to the next, as the Government of Manitoba notes. Learn more about how a cockroach infestation starts and where cockroaches come from.

How Fast Does a Cockroach Infestation Grow?

A cockroach infestation grows fast because each egg case holds dozens of eggs. A German cockroach egg capsule usually holds 30 to 48 eggs, and the female carries it for several weeks before dropping it in a sheltered crack, according to Penn State Extension. The young (nymphs) usually go through several molts before they become adults. The Government of Manitoba notes that an infestation can produce hundreds to thousands of cockroaches per year. If the numbers seem to jump overnight, read why there are suddenly so many cockroaches in your house.

Does a Cockroach Infestation Mean Your Home Is Dirty?

A cockroach infestation does not necessarily mean your home is dirty. Health Canada states that their presence does not necessarily mean conditions are unclean. What matters to cockroaches is food, water, warmth and hiding places, which even a well-kept home can offer. Crumbs, dirty dishes and leaks can still help an infestation grow faster.

What Are the Signs of a Cockroach Infestation?

A cockroach infestation leaves physical traces long before you see many roaches, because cockroaches hide during the day. According to UC IPM (University of California), the main signs are dark spots or smears of droppings, cast skins, egg cases, and live or dead cockroaches.

Cockroach Droppings

Cockroach droppings are one of the most common signs of roaches. Small species such as the German cockroach leave droppings that look like ground pepper or coffee grounds, while larger species leave small pellets that resemble mouse droppings, only slightly smaller (Orkin Canada). Look along cabinet edges, in drawers, behind appliances and in corners. UC IPM notes that the droppings contain a pheromone that attracts other cockroaches, so clean them up once you have noted where they are.

Smear Marks

Smear marks are dark, irregular streaks of droppings on surfaces where cockroaches rest or travel. You usually find them in humid spots, such as under sinks, along the wall where it meets the floor and around pipes. UC IPM notes that German cockroaches leave stains on surfaces they contact.

Egg Cases

Egg cases (oothecae) are small, hard capsules that hold the eggs. Their size and colour vary by species, according to UC IPM:

• German cockroach: light beige, about 1/4 inch (about 6 mm), usually carried by the female until shortly before hatching
• Brown-banded cockroach: light brown, often glued to ceilings or under furniture
• Oriental cockroach: dark red-brown, about 3/8 inch (about 1 cm)
• American cockroach: brown when laid, turning black, about 3/8 inch (about 1 cm)

Finding egg cases means cockroaches are breeding in your home, not just passing through.

Shed Skins

Shed skins are the empty, light brown outer shells left behind each time a nymph molts. German cockroach nymphs molt six to seven times before adulthood (Penn State Extension), so a growing population leaves many skins in cracks, cupboards and behind appliances. Shed skins are also a source of allergens, so vacuum them up.

Musty Smell

A musty smell can be a sign of a large cockroach infestation. Penn State Extension explains that high populations can produce a characteristic odour from the secretions cockroaches release, and Iowa State University Extension describes a musty "cockroach odour" in very heavy infestations. The smell is often strongest in closed cupboards, under sinks and in pantries.

Cockroaches in Daylight

Cockroaches in daylight are a warning sign. Cockroaches are mostly active at night, so seeing them during the day may point to a heavy population or to stress, such as a lack of food or water (Penn State Extension). The Government of Manitoba also notes that seeing a cockroach in a brightly lit area or during the day may be a sign of an infestation.

Dead Cockroaches

Dead cockroaches are listed by UC IPM among the signs of an infestation. A few dead roaches under the fridge, in the bathtub or along baseboards suggest that live ones are hiding nearby, especially if you have not used any insecticide.

Where Should You Look for Signs of Cockroaches?

Signs of cockroaches concentrate where warmth, moisture and food meet, so start in the kitchen. A flashlight helps you see roaches hiding in cracks and under counters (UC IPM). Checking a few minutes after you turn the lights on at night gives you the best chance of catching them in the open. For a room-by-room checklist, see how to find cockroaches and their hiding spots.

Kitchen

The kitchen is the first place to check. Penn State Extension notes that German cockroaches are usually found near dishwashers, stoves and sinks. Look behind and under the fridge, inside the cabinet under the sink, in the hinges of cupboard doors and around the pantry.

Bathroom

The bathroom gives cockroaches water and warmth. Check under the sink, around the base of the toilet, behind the tub panel and around pipes that go into the wall.

Basement

The basement is where Oriental and American cockroaches are often found, because they tend to prefer damp spots such as basements and drains (UC IPM). Check floor drains, sump pits, laundry areas and around the water heater.

Furniture

Furniture is where brown-banded cockroaches hide. UC IPM notes that they often hide behind artwork, inside appliances, in hollow furniture legs and in clutter, and glue their egg cases to ceilings or under furniture. If you find signs in bedrooms or living rooms far from water, check picture frames, the underside of tables and chairs, and electronics.

Using Sticky Traps to Confirm Signs of Roaches

Sticky traps are the simplest way to confirm signs of roaches and find where they are coming from. Health Canada notes that traps help you monitor numbers and locations, so you know where to focus control. UC IPM recommends placing them where the floor meets the wall and near suspected activity, numbering each trap and checking them daily for several days, since many roaches are caught within the first 24 hours. Penn State Extension suggests ten or more sites for one week. The trap with the most roaches points you toward the main hiding spot.

Which Cockroach Is Behind Your Infestation?

Four cockroach species commonly infest Canadian homes: German, Oriental, American and brown-banded. Knowing which one you have tells you where to look and which control method has the best chance of working. For photos and a full comparison, use our cockroach identifier.

German Cockroach

The German cockroach is the most widespread cockroach in Canada (Orkin Canada) and one of the most common household cockroaches in the world, according to Health Canada. It measures about 1.3 cm to 1.6 cm, is tan to light brown, and has two dark parallel streaks behind the head. It has wings but cannot fly. Health Canada notes that it is not very tolerant of cold, yet it has been found in buildings as far north as Nunavut.

Oriental Cockroach

The Oriental cockroach is a large, almost black cockroach, according to UC IPM. It lives in cool, damp places such as basements and drains, and it cannot climb smooth vertical surfaces. People often call it a "water bug".

American Cockroach

The American cockroach is the largest common species and is reddish brown (UC IPM). It is common in sewers and storm drains and prefers warm temperatures, so indoors it usually turns up in basements and around drains.

Brown-Banded Cockroach

The brown-banded cockroach is small, about 0.5 inch (about 1.3 cm), with light bands across its body. UC IPM describes males as golden tan and females as darker brown. It prefers warm spots away from the kitchen, such as furniture, appliances and the backs of pictures, and it is especially hard to control with baits.

Is a Cockroach Infestation Dangerous?

A cockroach infestation is mainly a health concern because of allergens and germs, not structural damage. Health Canada notes that cockroaches rarely damage buildings, but they can contaminate food and spread disease.

Cockroach Allergens

Cockroach allergens come from their droppings, saliva, shed skins and body parts, according to the Government of Manitoba, and the University of Kentucky notes that they can cause asthma and allergic reactions. UC IPM adds that indoor infestations are a risk factor for childhood asthma, especially in multi-unit housing, and that allergen levels rise with the number of cockroaches. Penn State Extension lists skin rashes, watery eyes, sneezing and nasal congestion among the reactions. If someone in your home has symptoms, talk to a health-care provider, and use a vacuum with a HEPA filter to clean droppings and skins.

Germs on Food

Germs on food are the other risk. Cockroaches walk through garbage and drains, then over counters and food, and Health Canada notes they can contaminate food and spread disease this way. UC IPM notes they may transmit bacteria such as staphylococcus and streptococcus, and the Government of Manitoba also lists salmonella and E. coli. Throw away food that roaches have reached and wash dishes left out overnight before using them.

Do Cockroaches Bite?

Cockroaches rarely bite people. The Government of Manitoba and NPIC say they are unlikely to bite, but their legs can scratch skin.

What Should You Do After Spotting Cockroach Infestation Signs?

Cockroach infestation signs call for two things at once: removing the food and water that feed the roaches, and using a slow-acting bait rather than a spray. Health Canada advises combining intensive cleaning with pest control products, because products alone will not succeed. For the full step-by-step plan, read what to do if you have cockroaches.

Remove Food Sources

Removing food sources makes every other step work better. Health Canada recommends these habits:

• Store food in tightly sealed plastic or glass containers, not paper or cardboard
• Clean up spills right away and do not leave pet food out all day and night
• Do not let dirty dishes pile up overnight
• Keep garbage in a sealed container and take it out often
• Vacuum often, including beneath and behind appliances
• Repair leaks, ventilate the bathroom and dehumidify damp areas

Use Baits Instead of Foggers

Baits are the most effective tool you can use yourself. UC IPM calls baits the primary pesticide tool for cockroaches and notes that they work better than sprays, although results often take 7 days or longer. Health Canada says bait stations kill cockroaches about 48 to 96 hours after they eat the active ingredient. Avoid foggers: Penn State Extension warns that residual sprays and aerosol foggers are of little value and may scatter cockroaches, making control harder. Before you buy, check that the label lists cockroaches and shows a PCP number, which means Health Canada has approved the product. Keep baits out of reach of children and pets. Our picks for the best cockroach killer can help you choose.

Seal Cracks

Sealing cracks cuts off hiding spots and entry points. Health Canada recommends caulking cracks, crevices and pipe openings, and covering vents, open pipes and drains with fine mesh screens.

Tell Your Landlord

Telling your landlord right away is essential if you rent. The Government of Manitoba advises tenants to report a suspected cockroach problem immediately, notes that landlords are generally responsible for dealing with it once informed, and asks tenants to cooperate with the treatment plan. It also warns that treating with store-bought chemicals yourself can spread roaches to other units, and NPIC also cautions against chasing them into other apartments.

When to Call a Pest Control Professional

Calling a licensed pest control professional makes sense when you see roaches in daylight, find signs in several rooms, live in a multi-unit building, or see no improvement after a few weeks of cleaning and baiting. Licensed technicians can find nesting areas and apply products not sold to the public (Government of Manitoba). A typical professional visit starts with an inspection to identify the species and hiding spots, followed by baiting or dust treatments and follow-up checks. Learn what cockroach pest control involves, or get a quote from a recommended local exterminator through Pest Agent's referral form.