How to Get Rid of Outdoor Roaches – An Integrated Pest Management Action Plan
The most effective and ecologically responsible method for controlling pests in your home is an Integrated Pest Management (IPM) approach. When large cockroaches find their way inside your home, crawling on your walls, kitchen counters, and showers, treating with IPM principles will solve your problem. Integrated Pest Management philosophies call for thoroughly inspecting and cleaning the infested area, locating and repairing the insect entry hole, and if necessary, applying a pesticide bait. The highly effective methods described in this article will get rid of the roaches from your home and prevent them from coming in again.
Types of Outdoor Cockroaches
Many species of cockroaches live outdoors and sneak into our homes and businesses if given the opportunity. These outdoor roaches do not breed indoors like German roaches do, but if given access to the structure, and food and harborage is readily available inside, these outdoor roaches can make pests of themselves. Several of the most common outdoor roach species will be described below, but they share many similarities.
These outdoor cockroaches are usually active at night and hide in harborages during the day. Outdoor cockroaches are more common in warm climates and they often burrow in moist surroundings such as leaf litter, mulched beds, palm trees, and dead and decaying wood. Outdoor roach populations can grow quite large if left uncontrolled. Given the fact that outdoor roaches often walk through dead animals and fecal matter, they can spread bacteria on the surfaces of your home. Often, a large number of outside roaches indoors, indicates the necessity of pest-proofing entryways such as doors and windows.
- Species: Periplaneta americana Linnaeus
- Size: 3 inch
- Color: brown to reddish brown
- Behavior: Often enter buildings through dry drains or broken plumbing lines.
- Habitats: landscaping, but also city sewers and basements, particularly around pipes and drains.
- Key Characteristics: cream-colored border on the pronotum (head shield), wings of males extend slightly beyond the abdomen, wings of females are about the same length of the abdomen. Enter buildings around doors, windows, and plumbing breaches.
- Species: Periplaneta australasiae Fabricius
- Size: 1 ¼ – 1 3/8 inch
- Color: reddish brown to dark brown
- Behavior: Large populations live in landscaping and most commonly enter buildings through gaps around doors and windows.
- Habitats: outdoors and in greenhouses.
- Key Characteristics: dark “Batman” pattern on the pronotum (head shield), light, comma-shaped cream colored bar on the front edge of each wing, sometimes referred to as “shoulder pads”, wings cover abdomen.
- Species: Periplaneta fuliginosa Serville
- Size: 1 ½ inch
- Color: dark reddish brown to black
- Behavior: Most commonly enter buildings through gaps around doors and windows.
- Habitats: tree holes, loose bark, and mulch.
- Key Characteristics: pronotum (head shield) is a solid dark color, wings cover the abdomen.
- Species: Blattella asahinai Mizukubo
- Size: ½ to 5/8 inch (adults)
- Color: Light brown to tan
- Behavior: Can fly and are attracted to light. Typically enter structures by flying toward lights and entering around doors and windows. Do not reproduce indoors like German cockroaches.
- Habitats: outdoors in shaded mulched or composted areas
- Key Characteristics: look almost identical to German roaches but behavior is very different.
Florida Woods Cockroach
- Species: Eurycotis floridana (Walker)
- Size: 1 1/16 – 1 3/5 inch (adults)
- Color: reddish brown to black
- Behavior: Rarely enters air-conditioned buildings, but is commonly found in the surrounding area. Produces foul-smelling defensive chemicals when disturbed.
- Habitats: in structures near the home, such as storage areas, greenhouses, shelter boxes for other structures, or under logs and rocks.
- Key Characteristics: wingless, well developed cerci and tooth-like projection, and slow moving.
- Species: Blatta orientalis Linnaeus
- Size: 1 inch
- Color: dark brown to black
- Habitats: outdoors and lives in warm, damp shady areas near the ground or any area containing natural debris.
- Key Characteristics: wings of males do not extent to the tip of the abdomen leaving the last 1/4 of the abdomen exposed, females do not have developed wings and only differ in appearance from large nymphs by having venation on the wing stubs.
- Species: Blatta lateralis Walker
- Size: 1 1/6 inch
- Color: reddish or orangey brown
- Behavior: The males of this species are attracted to lights.
- Habitats: meter and irrigation boxes and exposed compost piles.
- Key Characteristics: males have wings that cover the abdomen and are yellowish tan in color, females have short, rounded wings with creamy stripes along the edges and a pear-shaped body.
Water Bugs and Palmetto Bugs
Colloquially, the American cockroach and other large cockroaches are often called by regional names. Often, pest control technicians know the local lingo and act accordingly. Many areas of the country refer to this large roach as a water bug or a flying water bug. This is problematic as a true water bug is a different insect species entirely. In the southern United States, you will hear any large roach referred to as a palmetto bug. Some people refer to large outdoor roaches as Croton bugs, but this term is usually reserved to smaller German roaches. Scientifically speaking, local linguistics can add layers of confusion to cockroach identification.
Baby Cockroaches or German Roaches
German cockroaches are small and live almost exclusively indoors. They breed and reproduce indoors; many German roaches never see the sunlight; therefore they are referred to as domestic cockroaches. The treatment methods for roaches that primarily live outdoors and occasionally sneak inside (peridomestic roaches) is different than the treatment recommendations for German roaches. Often baby Asian or American roaches sneak indoors and because of their small size, people assume they are dealing with a German roach infestation. Proper identification of your roach specimen is crucial for a successful treatment. Your Pest Management Professional or local extension office can help you accurately identify the roach.
What do Outdoor Cockroaches Eat?
Roaches are omnivores, meaning they will eat both meat and plants. Although they are not picky, they prefer greasy foods, meats, sweets, and starches. They eat dead and decaying organic matter such as leaves and wood. American cockroaches are often found in the sewer where they feast upon the human waste found therein. Roaches have been known to eat book binding, paper, and wallpaper paste. Some roach species can go up to one month with no food, but they must have regular access to water. In cases of extreme starvation, some species of roaches will eat their own young, but this is rare, as they are pretty efficient scavengers.
Where do Cockroaches Come From?
When you run across a large American or Australian roach in the night, they have usually come from outside. They slip under a small crack in the door or window and scurry away when you turn on the bathroom light. They may enter in search of food, or extreme weather may have forced them up and into your home. Outdoors, cockroaches often burrow in moist shady areas of your landscape such as mulched beds, dead trees, wood piles, compost piles, or under leaf litter. Roaches are attracted to areas that offer hiding spots during the day and moisture. A leaky faucet dripping into a mulched bed will almost certainly house outdoor roaches.
American cockroaches in particular have adapted to find the sewage system a very hospitable place. There are countless American roaches crawling through the sewage system. If the system is in perfect working order, they usually stay in the sewer. However, if there is a break in the sewage line or some other structural issue, American roaches can crawl up through the sewage system and into your bathroom. In a severe American cockroach infestation that does not respond to traditional treatments, the sewer as the source of the roaches must be explored. Be prepared to hire a licensed plumber to perform a smoke test and repair any damage if found.
If the roach infestation is concentrated in a bathroom or kitchen with a drain that is rarely used, try running water down that drain at least once a week. Sometimes, when you come home from an extended trip, roaches may be running rampant. Run water down each drain to get water in the U-trap and prevent roaches passage into your home.
Life Cycle of Outdoor Cockroaches
Roaches develop through 3 distinct phases, egg, nymph, and adult. The timing of development is different depending upon the species of roach and the environmental conditions. Most roaches carry their eggs in a case, also called ootheca, attached to her body. She will then place the egg case in a hidden location. Eventually, nymphs or immature/baby roaches emerge from the egg case. The nymphs shed their exoskeleton multiple times, each time growing larger and looking more like an adult roach. Upon their final molt, baby roaches (nymphs) become adults with wings and they are capable of reproduction. American and Australian roaches live about 1 year, while Asian and Oriental roaches have shorter lifespans at less than half a year.
How to Get Rid of Cockroaches – IPM
Integrated Pest Management begins with a thorough inspection and sanitation of the infested premises. This baseline inspection will serve as a gauge to measure the success of your treatments. As you monitor the roach populations and implement control measures, you will see the results of a pest free home. Often, outdoor roach control can be taken care of with outdoor perimeter treatments, no pesticide applications indoors. By carefully sealing up entry areas and treating the roaches outdoors where they prefer to live, the IPM principles described below will be effective.
Preventing Cockroaches – Inspection, Monitoring, and Sanitation
The inspection, sanitation, and monitoring phase of Integrated Pest Management is an ongoing process. Many homeowners keep insect monitors hidden under cabinets and check them periodically. By being aware of the conditions that roaches and other insects are attracted to and catching pest introductions early, much time and hassle is saved. Once you have begun making changes and treatments, assess your results and be prepared to go further if warranted.
Cockroaches are nocturnal, so you may think you are wasting your time snooping around for roaches in the daytime. However, roaches leave evidence of the presence in a few different ways. Use a flashlight and all of your senses. Roaches are thigmotactic, preferring to harbor in locations where they have surface contact on both upper and lower body surfaces. That is why they hide in tight crevices such as the space between wall mounted fixtures and the wall or within cardboard boxes. They prefer dark moist locations so bathrooms and kitchens are usually the first to become infested.
During your inspection look for evidence of a cockroach infestation including:
- Live cockroaches
- Egg cases
- Depending on the species the ootheca may be between 5-10 mm, oval shaped, and usually between tan to brown in color.
- Feces may be wet or dry depending on the environment.
- In humid environments, these cockroaches will leave dark smears of fecal material.
- In drier environments, they will leave fecal pellets (resembles coffee grounds).
- Odor – A severe roach infestation has a specific recognizable odor. Once you have smelled it, you can recognize the distinctive odor.
Inspections should focus on areas where food and water are present, including:
- Kitchens and food storage areas
- Under cabinets, especially cabinets with plumbing inside
- Under appliances such as refrigerators, stoves, microwaves, toasters
- In and around floor drains
- Bedrooms, if food and drink is permitted into the bedroom.
Inspect groceries and delivery boxes for roaches before bringing them into your home.
- Produce and unsealed food products are especially susceptible.
- Cockroaches particularly like to hide in cardboard. Remove products from cardboard boxes in the receiving area and store packages on raised shelves or use plastic bins if needed.
Inspection practices should include checking for unsealed openings such as:
- missing or loose pipe and conduit escutcheons
- unsealed edges around sinks and cabinets
- unsealed edges of bulletin boards or wall-mounted electrical panels, mirrors, light fixtures, fire alarms, or emergency lighting.
Setting Monitors for Roaches
The number one monitoring tool for cockroaches is an adhesive-coated, cardboard insect monitoring trap, also known as a “sticky trap”. These insect monitors come in different sizes and shapes, depending upon your needs.
Here are some tips for effective monitoring:
- Monitors should be kept out of view if possible. Monitors may be secured with double-sided tape.
- Monitoring stations or units should always be dated at placement so that monitoring duration is known upon station recovery.
- Create a map of the area that includes the location of the traps. You may also leave space on the map to write numbers of insects per trap for each inspection. It also may be helpful to use monitor locators such as colored stickers.
- Monitors should be replaced if full or if the monitor has been wet or is covered in dust.
- If a trap is consistently empty, the trap may need to be relocated to another site. If you are seeing roaches but monitors are empty, the monitors are not correctly placed.
- Place fresh traps at the locations indicated on your map and count the number of cockroaches in the traps after 24 hours.
- Vigilance is important and good record keeping will save time and energy.
Why should I monitor?
- Monitors provide valuable information about the location and severity of pest activity.
- They allow you to detect roaches early before you have a full-blown infestation.
- Inspection and treatment time can then be better focused in these areas.
How many monitors should I use?
- The more monitors you use, the more detailed the information about pest activity you will gain, so use a sufficient number. Food service areas should have more monitors than nonfood areas.
- Monitor numbers will vary according to the size of the home or business, number of storage and electrical closets, size of food preparation and storage areas, and other areas that are not used on a daily basis.
Where are monitors optimally placed?
- Monitor location is extremely critical. Monitors should be placed in clean, dry areas close to any suspected cockroach harborages, entry points, or along the structural lines that roaches may travel between resources (e.g., harborage, food, water).
What kind of information can monitors give me?
- Monitoring should be used to pinpoint sites of infestation, treatment efforts should be concentrated at these locations.
- Monitoring should be used in all areas prone to cockroach infestation or introductions. Catching more than a single, isolated cockroach inside the building justifies an inspection to find out how they are entering the structure, find areas that are not up to sanitation standards, and locate other conducive conditions.
- Keep in mind that each egg case may contain 14 to 24 eggs, a localized “infestation” of several nymphs may actually be an “introduction” of a single egg case the hatches.
- A week or two after treatment, monitors should again be placed at the infestation sites to see how well the treatment efforts are working.
- If the trap catch has dropped considerably, the cockroach population has declined and progress has been made. If not, another treatment strategy should be considered and greater efforts must be made to eliminate food, water, and harborage resources.
- To assess the continued success of treatments and detect any new infestations, continue to monitor after the IPM program is underway.
Cleaning to Prevent and Get Rid of Roaches
Eliminating food, water, and harborage (i.e., the survival triangle) is key to successful cockroach control.
- Clean up food and drink spills immediately.
- Wipe surfaces with soapy water followed by a water rinse. The soapy water and rinse helps to remove cockroach allergens and aggregation pheromones left by cockroaches to attract other cockroaches to an area.
- Inspect kitchens, bathrooms, and bedrooms for cleanliness and remove food trash at the end of each day.
Potential food sources
- Eliminate food sources that can compete with bait applications.
- Enforce all food rules of the household. Ideally, food should be limited to the kitchen and the dining room. Make sure all food is stored in plastic containers or sealed tightly in other types of pest-proof containers.
- Remove food products and food service supplies from cardboard containers as soon as they are delivered.
- Place exterior trash cans and dumpsters away from building entrances.
- Use liners for waste containers and empty at the end of the day so that food and food waste is not left inside overnight
Potential water sources
- Eliminate water sources that can compete with bait applications.
- Fix plumbing leaks, gutters that hold water and damp wood to eliminate access to water.
- Keep water in drains to keep filth and debris down. When on an extended vacation or anytime a drain is not in use, two drops of mineral oil in each drain will help keep water in P-traps from evaporating.
- Clean drains, cracks, and crevices with an enzyme-based cleaner.
- Eliminate clutter. Clutter creates harborage for pests. Harborage allows pests to eat, rest, and reproduce in the privacy and darkness of their own pesticide-free zone. Clutter makes it harder to clean.
- Put cardboard in outdoor recycling containers to avoid introducing cockroaches and egg cases.
- Inspect incoming products and reject any containing evidence of cockroaches, including cockroaches, feces, or egg cases.
Keeping Outdoor Roaches Outside – Physical Control
The above-mentioned cockroach species only breed in “outdoor conditions”. Unless you have an issue creating outdoor conditions inside (roof leak, plumbing leak, etc.), individual cockroaches must be entering from outside the structure. Excluding cockroaches from entering the building should be the first line of defense.
Seal all gaps where cockroaches could enter. If you can see even a small amount of light coming in around a door or window, then that is enough of a gap for a cockroach to enter.
Seal all sinks, baseboards, and cracks. Fix any holes or broken tiles.
Seal cracks and crevices in food storage, preparation, and serving areas.
Seal cracks between sinks and counters and walls.
Seal openings around the edges of electrical boxes, bulletin boards, and signage.
The most common ways outdoor cockroaches enter the structures are:
Gaps around doors and windows.
Replace missing and damaged weather stripping and door sweeps.
Leaving doors propped open.
Dry traps in sink or floor drains.
Breaches in sewer lines.
Hitchhiking on incoming shipments.
To prevent entry from sewers, pour water down every drain on a weekly basis to fill traps when the drain is not routinely used.
For older drains or areas where city sewer lines end, the installation of Trap Guards® can be used to keep sewer gases and American cockroaches out.
If a plumbing breach is suspected, a plumber can perform a “smoke test” on the building to detect any hidden breaches in plumbing lines that need to be sealed.
Position exterior lighting to avoid attracting cockroaches to building entryways at night. Use sodium vapor or yellow bulbs for exterior lighting to reduce attraction to cockroaches.
Typically when you encounter an issue with one of these species of cockroaches indoors, you are dealing with no more that a few individual cockroaches. A HEPA vacuum can eliminate the problem in a matter of seconds.
Traps placed at potential entry points (if not possible to block) may prevent entry of outdoor cockroaches. Adhesive coated sticky traps are the most commonly used cockroach trap.
What Products Kill Cockroaches
The preferred chemical management options are insecticide baits and Insect Growth Regulators (IGRs). These are low risk treatments that reduce the potential for exposure of people and pets to insecticides, furthermore, they are extremely effective. To control outdoor roaches, insecticide products rarely need to be placed indoors.
These species of cockroaches are typically outdoors. Focus treatment efforts around entry areas and in the landscaping surrounding the building. Granular baits are the most efficient and effective way to bait outdoors. They are applied outdoors around the perimeter of the building to reduce the outdoor population of these cockroach species before they have a chance to enter the building.
Always read and follow the label on the pesticide container. The label is the law. Pesticides must be used in accordance with federal, state, and local regulations. Applicators must have proper credentialing to apply pesticides and should always wear all personal protective equipment (PPE) that is specified on the pesticide label.
Boric Acid and IGRs for Outdoor Roach Control
For outdoor roach control, long-lasting granular insecticide baits applied to the perimeter of your home keep roach populations low near the entry points of your home. Any cockroach that is scavenging for food near your home for food will instead find the bait. Once he consumes the bait he will die. Insecticide baits combine a palatable food matrix with an active ingredient which causes the insect’s death. A common and highly effective active ingredient in these granular perimeter bait products is orthoboric acid. Boric acid is used in a number of products that we use every day such as laundry detergent and contact solution. It is safe for people and pets. However, when consumed by insects it is fatal. Boric acid blocks roach’s ability to produce enzymes and kills the microorganisms inside the roach’s stomach. Ultimately, the roach is unable to extract any nutrients from the food he has consumed and he starves to death.
As with any bait product, it is most effective when it is fresh. The majority of the product is a food based attractant which entices the roaches and other insects to consume the active ingredient. Therefore, it is important that your bait is fresh. Just as we toss a bag of stale potato chips, roaches are not tempted by old stale granular bait. If your roaches don’t eat your bait, they will continue searching for food and may end up in your kitchen.
With the availability of modern baits, IGRs, and sanitation, with an emphasis on the use of HEPA vacuums to quickly remove any stragglers, there is virtually no reason to use residual sprays indoors for outdoor cockroaches. Perimeter baits work just as quickly as sprays to kill cockroaches and are found to be more effective in the long-term.
Roach Gel Baits for Outdoor Roaches
When dealing with German roaches, the most effective form of control is a bait formulated as a gel and placed indoors near the roach harborage areas. As stated above, when you are battling outdoor roaches such as American or Australian roaches, chemical treatments indoors are rarely necessary. Every pest situation is different, occasionally you may need to apply gel bait indoors for roaches that primarily live outside. In situations where it may take time to remedy an entry hole or leaky faucet, gel roach baits can kill these larger roach species as well. Particularly used in situations where roaches may be emerging from a broken sewer, indoor bait placements can reduce the population while you deal with the underlying issue.
Active Ingredient (AI)
Advion® Gel Cockroach Bait
22 – Sodium Channel Blocker
Alpine® Cockroach Gel Bait
4 – nAChR Agonist
Avert® Dry Flowable
6 – Chloride Channel Activator
Intice™ 10 Perimeter Bait
8 – Miscellaneous
Intice™ Roach Bait
8 – Miscellaneous
Invict Gold™ Cockroach Gel
4 – nAChR Agonist
20 – Mitochondrial Complex III electron transport inhibitor
4 – nAChR Agonist
2 – GABA antagonist
Maxforce® FC Select
2 – GABA antagonist
Niban® Granular Bait
8 – Miscellaneous
Vendetta® Cockroach Gel Bait
6 – Chloride Channel Activator
Abamectin + Pyriproxyfen (IGR)
6 – Chloride Channel Activator
7 – Insect Growth Regulator
*= IRAC Classification is a system grouping similar insecticides. Rotations should include products of different classifications.
Natural Cockroach Repellents
There is no reliable scientific evidence that the home remedies hailed by the internet can take care of an infestation of large cockroaches. If your home or apartment has conditions that attracts roaches and feeds them and supplies them with a regular supply of water, the cinnamon or pulverized bay leaves you sprinkled on your counter top will not deter the roaches. Perhaps you will kill a roach sprayed directly with a high concentration formula of rosemary or tea tree oil, but you have not addressed the root cause of the infestation. Some of the suggestions, such as leaving beer soaked bread on the counter, may actually cause other insects to infest the area.
The most natural and effective answer to outdoor roaches is implementing an IPM program as outlined above. Reduce clutter and access to food and water. Take the time to seal your home properly to prevent the outdoor critters from gaining entry. If necessary, use a safe boric acid insecticide bait to kill the roaches before they enter your home.