German Cockroach – An Integrated Pest Management Overview

German roaches are often the little creatures scurrying across your bathroom or kitchen at night. In the early stages of a German roach infestation, you may simply assume that a small roach from outside has made it inside, squish the roach, and forget about it. However, given enough time, German cockroach populations can become quite large and thoroughly infest your home. With a bit of information on German roach biology and behaviors, you can learn how to get rid of German roaches and keep them from coming back.

German roaches are best controlled by closely adhering to the tenants of Integrated Pest Management or IPM. IPM is a more holistic approach to pest control. Gone are the days of blanket spraying all baseboards in your house with pesticides. Aggressive interior spraying for German roaches was never thoroughly effective anyway. Integrated Pest Management teaches us to reduce the use of pesticides and take the environment and fragile ecosystems into account when we devise our pest control plans. The IPM Institute of North America defines Integrated Pest Management as, “a sustainable, science-based, decision-making process that combines biological, cultural, physical and chemical tools to identify, manage and reduce risk from pests and pest management tools and strategies in a way that minimizes overall economic, health and environmental risks.”

IPM for German roaches favors baits rather than sprays. IPM for German roach control involves reassessment of your control measures. By using multiple control methods, assessing the results, and making changes if needed, you will be able to completely eliminate a German roach infestation.

German Cockroach Lifecycle/Identification

Adult German cockroaches, Blattella germanica L., are small, between 1/2 to 5/8 inches long with wings. They have two dark stripes that run parallel from behind their head to the base of their wings. For the layperson, the most obvious characteristic of German cockroaches is their small size. These are not simply baby American roaches and can not be treated as such.

• German cockroaches do not enter structures from outdoors. They live and breed indoors.
• They are spread entirely by humans and live only in association with people.
• German cockroaches are the most prolific cockroach species, producing 3 to 6 generations per year.
• German cockroaches prefer to spend most of their lives in cracks and crevices, near sources of food and water.
• They are most active at night. If they are seen during the day, this is a sign of a severe infestation.
• German cockroaches are used by health departments as a sign of poor sanitation and may result in a failed health inspection.
• German cockroaches produce at least 1 dozen distinct allergens that are potent triggers of asthma.

The German roach life cycle has 3 stages: the egg, nymph, and adult. The life cycle can be completed in about 100 days, but it is dependent upon many factors such as temperature, availability of food, water, and harborage. In a given infestation, usually 80% of the roaches are nymphs (juvenile) and 20% are adult. German roaches breed continuously with overlapping generations living together. The reproductive capacity of these roaches is astounding, therefore early intervention and treatment is the best policy.

German Roach Eggs

Although most homeowners will never inspect a roach this carefully, female German roaches can be observed carrying their ootheca, or egg case. The yellowish-brown egg case protrudes from her backside or abdomen.

• In her lifetime, each female may produce between 240 – 320 offspring:
  • About 1 ootheca per month, or 8 ootheca in her lifetime.
  • Each egg case contains between 30 – 40 nymphs.
    Therefore, if just one female with an egg case is brought into your home, it quickly becomes a cause for pest control intervention.

German Roach Nymphs/Babies

Nymphs, or juvenile roaches, are often darker in color than the adults with two prominent dark stripes surrounding a lighter, tan spot or stripe on the body. German roach nymphs do not have wings and they start out very small, about the size of a pin head. As they progress through this juvenile stage, they mature and change shape and size. During this immature phase, German roach babies usually molt 6 separate times. In addition to fecal matter, it is the accumulation of these discarded exoskeletons that often trigger asthma and allergies.

At the conclusion of the nymph stage (usually about 60 days), these roaches are full-grown adults with wings and capable of reproduction.

German Cockroach Images

German Cockroach vs American Cockroach

As discussed, adult German roaches are small and live and breed indoors. However, they are easily confused with baby roaches of different species. It is important to accurately identify your species because treatment methods are different. If you are treating baby American roaches as if they are German roaches, you will not have great success.

Baby American or Australian cockroaches can sneak under the doors or through cracks in windows and masquerade as German roaches. Just because you see a small roach, that does not necessarily mean you have German cockroaches. Baby American roaches are approximately 1/8” when they hatch. They start this phase a whitish color and just a few hours their exoskeleton hardens, and they progress to grayish then reddish brown. Very quickly after hatching, American cockroach nymphs look very similar to American cockroach adults, only smaller. If you need help, your local extension office can accurately identify the roach species so that you properly target the species of roach that you actually have.

How to Get Rid of a German Roach Infestation

By utilizing the tenants of Integrated Pest Management, you can get rid of German roaches. The first level of treatment for German cockroaches includes the inspection, sanitation, and monitoring. A thorough inspection ensures you have accurately identified the cockroach species, it also tells you where the infestation is concentrated, and how severe the infestation is. Without proper sanitation, German cockroach infestations will be more difficult to eliminate and prevent. Effective and regular monitoring ensures the cockroaches are eliminated and helps catch a reoccurrence early should it occur.

The second phase of an IPM plan for cockroaches involves any physical or mechanical controls. This includes sealing entry areas, eliminating harborage areas, and physically removing German roaches with a HEPA filter vacuum cleaner.

The third phase of getting rid of German cockroaches involves using reduced exposure treatments. The preferred chemical treatments for German roaches are baits and Insect Growth Regulators, or IGRs because they are the most effective treatment for German roaches.

Each of these phases of treatment will be discussed in detail below.

Inspecting for German Roaches

A thorough German roach inspection is one of the most important aspects of getting rid of German cockroaches. Take your time during this inspection so that nothing is missed. At the conclusion of your inspection, you should know where the roaches are concentrated, how widespread the infestation is, and make note of areas that can be repaired or fixed to eliminate conducive conditions. Always keep a watchful eye; inspections can actually help to prevent infestations.

• Be aware that people can carry German cockroaches into an area on backpacks, purses, lunchboxes, and other clothing items.

German cockroach inspection should focus on pest vulnerable areas where food and water are present. Use all your senses when looking for cockroaches, except perhaps taste! Use a flashlight and mirror to help you see. Cockroach infestations have a distinctive odor due to their feces and pheromones; if you cannot see them, maybe you can smell their presence. You will need to touch and move items to find the German cockroach harborage. You may need to physically remove wall plates or the dishes from the cabinet. You will even use your sense of hearing. Listen for dripping faucets that allow excess moisture to accumulate.

Pay special attention to equipment where heat is generated: behind refrigerators and freezers, ovens, stoves, and electrical junction boxes.

• Inspection practices should include checking for unsealed openings such as:
  • Missing or loose pipe and conduit escutcheon plates
  • Unsealed edges around sinks and cabinets, wall-mounted electrical panels, mirrors, light fixtures, fire alarms or emergency lighting.
  • Hollow-legged tables and chairs that are not sealed.

German Roach Droppings

German roaches congregate in tight cracks and crevices near heat and moisture. When inspecting for German roaches, keep an eye out for evidence of roach fecal matter or poop. German roach poop looks like ground pepper or coffee grounds. These droppings can trigger allergies and asthma and are often found in the tight crevices where roaches like to hide. German cockroach droppings may stain a cabinet or countertop and has a distinct odor. Many experienced pest control operators can smell evidence of German roaches before they visually find them.

Monitoring for German Roaches

Insect monitors are thick card stock with a sticky adhesive. These monitors are often perforated and can be folded or torn into different sizes depending upon the demands of the space. When properly placed, insect monitors trap insects that may be walking through a particular area. These monitors are often preprinted with a space where you can write the date and the location that you placed the sticky trap. By properly utilizing this valuable tool, you have “eyes” inspecting the area 24/7. Sticky pest monitors will tell you how effective your treatment efforts are; if your roach population is going up, going down, or remaining stagnant.

We recommend you create a map of the area to be monitored or treated for roaches. Include on this map anywhere you have placed a pest monitor. Always date and number monitors for documentation purposes. Each time you check your monitors count the insects and log in either on your map or in a pest journal. Replace the monitors if they are full, wet, or covered in dust.

What kind of information can monitors give me?

• Look carefully at the insect monitor. If you have captured, adult roaches, juvenile roaches or nymphs, and maybe even a female with an attached egg sack you know this is an established infestation that has been present for some time.
• If you only capture one to a few adults, you are likely dealing with a new introduction and have caught this problem early.
• If you captured a few very small young nymphs, the harborage is likely nearby. Focus your inspection within 5 to 10 feet away from the monitor to identify possible harborages or sources of infestation.
• Monitors can give you an indication of which direction the cockroach came from in order to better focus inspections.

Where Should I Place Insect Monitors for German Roaches?

• In pest vulnerable areas including food storerooms and preparation areas, and anywhere else cockroaches have been a problem including laundry rooms, custodial closets, electrical closets, storage closets, staff lounges and student lockers.
• In addition to areas with food, water, and harborage, also focus monitor placements near areas where heat is generated. Check behind refrigerators and freezers, ovens, stoves, and electrical junction boxes, as these appliances often attract cockroaches because of the heat they give off.
• Place monitors in dry areas along structural lines, adjacent to walls, corners etc., where cockroaches travel, and close to suspected cockroach harborages. If they are not placed correctly, monitors will only trap a fraction of the cockroaches that they otherwise could if placed properly (Fig. 9).

Kitchen Sanitation for German Roaches

Food, water, and harborage are essential for German roach reproduction and success. By eliminating access to these 3 factors, also called the survival triangle, German roaches will be easier to control and prevent. Because of their food and water requirements, German roaches are most commonly found in the kitchen and bathrooms. When treating German roaches pay particular attention to cleanliness of your kitchen, and once the infestation is under control, continue the positive changes in your kitchen to prevent another infestation.

• General Cleaning
  • Clean often and systematically, paying particular attention to less accessible areas.
  • Use soapy water with a clean water rinse to remove cockroach allergens that are potent asthma triggers. No-rinse cleaners only spread allergens, they do not remove them.
• Remove potential food sources
  • Store food items in sealed containers, including art supplies (e.g., corn, beans, macaroni)
  • Clean up food and drink spills immediately.
  • Use thick trashcan liners, so that they do not break easily.
  • Empty trashcans containing food at the end of the day.
  • Clean drains, and cracks and crevices with an enzyme-based cleaner.
• Remove potential water sources
  • Ice makers, refrigerators, freezer drains, leaking pipes and faucets, food warmers, clothes washers, bathrooms are all areas that can provide water to German roaches.
  • Mold growing on walls or ceiling tiles are an indication of excessive moisture that may support German roaches.
• Remove potential harborages or nesting sites
  • Eliminate cardboard. German cockroaches thrive in cardboard.
  • Anything requiring storage for >3 to 6 months should be stored in plastic bins.
  • Simplify the environment so that cockroaches do not have a place to live and breed. Eliminating harborages also makes inspections and monitoring more efficient.

Physical/Mechanical Control for German Roaches

Once you have thoroughly inspected the problem area, evaluated the monitors that you placed, and cleaned the areas of cockroach activity, you can begin treatment. IPM principles require that before you jump to chemical treatments, physical and mechanical control first be implemented. These physical and mechanical control methods are often not sufficient to eliminate a German roach infestation, but they can greatly reduce the population, allowing for a quicker solution to the problem and the use of less pesticide.

• Eliminate the harborages by sealing cracks, sealing edges around wall-mounted electrical panels, light fixtures, bulletin boards, sinks, cabinets, etc., with caulk. Pay particular attention to areas around water and food preparation sites.
• Use a HEPA vacuum to remove heavy infestations prior to treatment. This provides immediate control, instant customer satisfaction, and reduces the infestation to a more manageable level.
• Use a nonchemical flushing agent, such as compressed air in cans used to clean dust from electronics. Direct air stream (often via a straw tip) into cracks and crevices suspected of harboring cockroaches. Vacuum up cockroaches as they emerge. Avoid the use of insecticide flushing agents because they will contaminate bait placements.

Reduced Exposure Pesticide Treatments – Roach Baits and IGRs

The preferred chemical management options for German cockroaches are insecticide baits and insect growth regulators (IGRs). Chemical options, including baits, should NOT be used on a routine or calendar-basis. Baits are most effective when they are freshly placed. Once a German roach infestation is under control, you will enter “maintenance mode” where you will only place fresh bait when roaches are found on insect monitors. The use of baits and IGRs decrease the probability of unnecessary pesticide exposure compared to surface sprays of contact insecticides.

Roach bait is most commonly formulated as a gel consistency and is pushed out of the tube and applied in small circlular placements. Roach baits contain both an active ingredient and food grade attractants. Roaches must consume the bait in order for it to effectively eliminate the roach infestation. Different active ingredients act upon the insect in different ways, and some roach baits are more palatable to roaches than others.

Roach baits work because they exploit roach’s natural behaviors. Roaches regularly eat each other’s feces, vomit, and even each other. When a roach that has consumed your bait placement either vomits, poops, or dies, other roaches in the nest will eat his excrement or his dead body. In doing so, they now consume enough of the active ingredient from the bait to kill them as well. This is called secondary transfer. Baits work to eliminate infestations better than sprays because early-stage nymphs do not leave the harborage sites to feed and will not contact the spray. Sprays are never able to reach the roaches in this young life stage, thus the life cycle continues. Baiting can reach these young roach nymphs within the walls, and therefore eliminate the entire infestation.

How Long Does Roach Baiting Take?

With the newer “fast acting” baits on the market control can be achieved in a matter of days. Baiting is now faster at control than old-fashioned sprays. Older baits took a week to kill roaches and typically you would wait a week to apply a different brand of bait to target any survivors. This process would be repeated 2-3 times and control would take up to a month if bait was thoroughly applied each time.

Newer bait formulations utilize fast acting active ingredients that kill roaches within 24 hours of eating the bait. A different brand of bait can be applied as soon as the next day to target survivors. Most roaches will be eliminated in the first couple days. A slow acting bait can then be applied to get any stragglers that remain after the first few days. Slow acting baits are slower, but have more time to transfer effectively to any remaining roaches.

The key is to thoroughly bait each time. Often bait is under applied and many areas are missed. This will prolong the time to control or even cause a complete treatment failure.

Roach Baiting Tips

• Always place baits according to the product label.
• Use information from the monitors to increase effectiveness and efficiency. If the monitors in a room do not contain cockroaches, it is probably not necessary to apply any product. If monitors indicate activity in just one part of a room, bait that section of the room.
• Use small more pea-sized applications of bait rather than long streaks of bait (i.e., do not use bait as if it were caulk)
• Keep your bait stored separately from other products that might contaminate it, making the bait unpalatable. Do not apply bait over areas that have been sprayed or are contaminated with harsh chemicals.
• Fresh bait is more palatable to cockroaches. In general, bait applications should be reapplied no longer than after 1 to 2 weeks to replace any bait that was consumed and to keep fresh bait constantly available.
• When applying fast-acting baits, you may even choose to apply a different bait daily to achieve rapid control.
• Continue placing bait until there are no more cockroaches, including nymphs or egg cases, found on the monitoring cards. At this point baiting can end. If you stop treatment before all the roaches are eliminated the life cycle will begin anew.
• Even though new baits are extremely effective when competing food is present, sanitation efforts must be maintained to ensure the roaches eat your bait, not your crumbs.

German Roach Product Selection

*Products listed are not endorsements, just examples.

Currently there are numerous cockroach baits on the market. They can be evaluated according to: time to kill, active ingredient (AI) class, formulation, and pricing.

• Baits such as Maxforce Impact and Advion™ Cockroach Bait kill cockroaches in as little as a few hours. These baits can be used for an initial “clean-out” to reduce the pest population quickly.
• Baits such as Vendetta Plus and InTice™ Roach Bait contain slower acting active ingredients. These baits are ideal choices in rotations because the cockroaches will live long enough for the bait to secondarily transfer to other cockroaches.
• Most German cockroach baits are gel formulations. Avert Dry-Flowable is an exception. It is a powdered bait (not a dust) that can be used in some situations. Dry-flowable products cannot be used everywhere that a gel bait can, but it is an excellent option in rotation with gel baits. There are also no issues with dry-flowable baits drying out and becoming less palatable as occurs with gel baits.

German Roach Resistance and Aversion and Product Rotation

When repeat applications are necessary, it is paramount that you rotate the product you are applying. Apply a bait with an active ingredient from a different insecticide class at least monthly. Each active ingredient works on the insect in a different way. Some are fast acting for immediate reduction in population and others are slower acting, allowing the roach to take it back to the harborage area. Proper product rotation will slow the buildup of product resistance.

Insecticide resistance is when cockroaches eat bait but do not die. Just as we deal with antibiotic resistant germs, some German roaches are not affected by a particular active ingredient. Insecticide resistance in cockroaches has been reported ever since we started doing cockroach control. Bait-aversion is where some cockroaches simply do not like the taste of a particular bait and will not eat it. Cockroach baits can contain sugars such as glucose that make the bait matrix palatable. In some German cockroach populations, glucose triggers “bitter” neuronal receptors to fire, causing cockroaches to avoid the glucose and baits containing glucose. Bait-aversion and bait resistance are inherited traits and are widespread enough that proper bait rotation should always be a part of a German cockroach IPM plan.

How do I create a rotation of different cockroach baits?

Insecticide Resistance Action Committee, or IRAC, has developed a classification system that groups similar insecticides. IRAC has assigned each EPA registered roach bait a classification number based upon the way that each active ingredient acts upon the insect. You should rotate roach bait products from different classes as indicated by the number assigned by IRAC.
Find the IRAC Classification column. Rotations should include products with different numbers as indicated by the number preceding the mode of action description.

• By rotating at least three baits with active ingredients from different IRAC classes you can reduce resistance and aversion.
  For example, if your German cockroach population is averse to the bait you use on your first treatment your insect monitors will not reveal a downturn in the population. For your second treatment, apply a different bait with a different IRAC Classification number. The roaches that were resistant or averse to bait #1, will eat bait #2 and die. Continue to use your insect monitors and document the locations and numbers of cockroaches captured. Rotate with at least 3 different baits until there are no more roaches.

Caution – Use only 1 bait at a time. Using different baits can cause cockroaches to ingest sublethal insecticide doses and actually cause resistance and cross-resistance building in populations.

Insect Growth Regulators (IGRs) for German Roach Control

Insect Growth Regulators, or IGRs, can be a valuable tool in the battle against German cockroaches. IGRs on their own do not kill roaches, however, they sufficiently disrupt the roach life cycle to warrant considering using an IGR product.

• IGRs prevent the normal development of immature cockroaches so they cannot reproduce as adults.
• When a female German cockroach is carrying an egg case, she does not feed and forage as often. She is therefore less likely to encounter a lethal bait placement. IGRs cause the egg case to release prematurely, which allows her to forage and feed normally; thus, increasing the probability that she will feeding on the bait.
• IGRs are most effective when applied as a crack and crevice treatment to cockroach harborages.
• To avoid contaminating bait placements, place bait close to but not on top of an IGR treatment to avoid the possibility of decreased bait palatability.

Read the label. Not all IGRs can be used close to food preparation surfaces, and some are volatile.

Do German roaches bite?

German roaches are omnivores, eating both meat and plants. They do not actively seek out humans to bite, and will generally not bite during a night-time chance encounter. However, in extreme infestations, German roaches have been known to bite eyelashes, fingernails, and eat food residue off of sleeping people’s faces. This happens only in the most extreme infestations, and immediate steps to eliminate the infestation should be put into place.

What NOT to do for German Roaches

With the availability of modern baits, IGRs, and sanitation, with an emphasis on the use of HEPA vacuums, there is virtually no reason to use the methods described below. However, they are available and may be touted as an option for German cockroach control on web forums or product reviews. It is important to be aware of some of the unintended consequences of some of these treatments.

• Fogging – A bug bomb you can pick up at the grocery store may sound tempting, but when activated the insecticide does not reach the cockroach harborage area. Bug bombs are not only ineffective, but they also coat your kitchen and bathroom counters with an unnecessary sticky insecticide residue.
• Surface sprays to known harborage areas – If you spray a residual insecticide on or near areas where you intend to bait, the spray will render the bait unpalatable and will not be consumed by the roaches.
• Insecticidal Dust – Many insecticidal dusts are labeled for applying to unreachable areas. However, carefully consider the location, any sensitivities, and the active ingredient of the dust. Dust applied behind a wall outlet will contaminate an area that may have been ideal for bait placement. Improperly applied, dusts can become airborne, contaminating off-target sites and non-target organisms, including people. Unnecessary exposure creates increased liability.

Natural or Home Remedies for German Roaches

The internet is full of articles telling you how to get rid of German roaches naturally. These ideas range from concoctions of peanut butter, sugar, and baking soda, to essential oils, and mopping roach infested areas with a vinegar solution. There is no scientific evidence that these methods can effectively eliminate a German roach infestation. In fact, these suggestions may push the roaches deeper into their hiding places and may contaminate locations that would make for excellent bait placements when you later decide to bait.

Boric acid is a natural substance and is toxic to roaches. Online you can find many natural roach remedies using boric acid. While it is true that boric acid can be an active ingredient in baits for roaches, it is difficult make at home a boric acid bait that is palatable. If you want to try boric acid as your active ingredient, purchase a commercially available bait product with specially formulated food components that is attractive to German roaches.

By following IPM protocols, monitoring your progress, and making changes or amendments when necessary, German roaches can be eliminated using baits, IGRs, and conscientious sanitation practices. IPM practices intentionally minimizes pesticide exposure while ensuring effective pest control.

FAQ’s