Despite their name, the German cockroach is neither native to Germany nor is it restricted to that region. In fact, they can be found throughout the tropical and temperate regions of the globe. Fossil evidence indicates that they have been around for over 300 million years and thanks to their highly adaptive nature, they have thrived in just about every environment.
Entomologists are of the belief that the German cockroaches originated from Southeast Asia and later hitchhiked with Marco Polo, as he traveled from Venice, Italy to Asia. These bugs later spread to different parts of Europe and eventually to almost all the warm and humid regions of the planet.
Today, approximately 3,500 species of cockroaches exist, with German cockroaches being the most commonly found species in houses, apartments restaurants, and industrial areas.
Recognizing the German Roach
In contrast to the typical Asian cockroach, one of the distinguishing features of German cockroaches are their inability to fly despite having fully developed wings, and a half inch long oval-shaped with three pair of legs and a pair of antennae. In terms of color, the adult German cockroach ranges from tan to light brown in color, with two distinct parallel lines running through the length of its body. The body of a male cockroach is thin and slender, with a tapered posterior abdomen which is visible and not covered with leathery outer wings called tegmina. The female, however, is comparatively stout with a round abdomen covered with tegmina.
Typically, German cockroaches take about six weeks to six months to reach maturity. The nymphs are similar in appearance to the adult except that they are smaller in size and don’t have wings. Moreover, these nymphs have a yellow patch on the center of their bodies.
The female carries the eggs in an egg sac which can be seen protruding through its genital chamber on the posterior end. The egg case is a brown purse shaped structure about 8 millimeters in length and contains 30 to 40 eggs. The nymphs often hatch from the egg case while the female is still carrying it. A female in her entire lifespan will typically produce 8 egg capsules. These three stages in the life cycle are completed within approximately 100 days, however, this time is bound to vary depending upon temperature, food availability and the type of species breeding. Under ideal conditions, they exhibit an exponential growth rate. A pair of German cockroaches can give birth to approximately 10,000 offspring in a year.
The German cockroach is one of the most successful group of pests present. It requires a hot, humid environment to propagate. They are found throughout the globe in association with human civilizations. They don’t have the ability to survive in areas away from the human population and also avoid the area with cooler temperatures. The major survival limiting factor is the food and water availability along with the temperature. Thus, an ideal environment would be one with an elevated temperature and humidity.
Though nocturnal in nature, they can be sighted in the daytime as well in places where their population is higher. Because they are small in size, they can easily sneak into residential areas, restaurants, and other food processing facilities through cracks and crevices in the doors or walls. They can easily climb smooth surfaces because of the presence of sticky pads called arolium on their feet. They can also hitchhike by easily concealing themselves in cardboard boxes, secondhand goods, and grocery bags. They will reside in areas near food and water and are omnivorous as far as their eating habits are concerned. They’ll particularly feed upon meat products, sugar, and starches. When the food becomes scarce, they will even survive on glue, soap, and wire insulations. In case of a famine, the German cockroaches have been observed to develop a cannibalistic tendency, feeding on their nymphs and chewing each other’s legs and wings. These omnivorous feeding habits make them highly adaptable to a wide variety of environments, consequently making their elimination a difficult task.
Health Risks and Nuisances
This urban invader is considered to be one of the most successful species of invader pests predominantly found in manmade structures. The German cockroaches are often known as filth roaches, because of their unhygienic feeding habits. They feed on human and animal excrement and move through all sorts of places including sewers, drains, washrooms, etc. Each and every part of their body is loaded with all sorts of disease-causing pathogens like bacteria, protozoans, and viruses, especially their legs and wings. Even a slight touch of these pests can transfer these pathogens to the food items resulting in severe food poisoning in the humans that consume such food. They are known to be carriers of organisms which cause diarrhea, dysentery, plague, leprosy, typhoid fever, cholera, and even polio.
As if this was not enough, they even carry eggs of six different kinds of parasitic worms which cause severe skin conditions like ringworm infections, skin rashes, dermatitis, itching of the eyelids, inflammation and even respiratory tract infections. Their droppings, skin casts and corpses cause allergic reactions like asthma and nasal congestion.
When excited or in stress, the German cockroaches are known to release foul odorous secretions from oval-shaped glands on their body and from their mouth, which establishes a long-lasting offensive smell in areas of infestation and in the food they have contaminated. They can also cause psychological disorders in humans such as stress associated due to the stigma associated with the infestation, which ultimately affects their overall behavior leading towards insomnia and depression. In highly infested areas, these roaches have also been reported to bite humans.
These roaches are thus not only an aesthetic problem but also pose serious health risks which make their prevention and elimination even necessary.
Why are German Cockroaches so Difficult to Control?
There was a time when the German cockroach was considered as one of the most difficult pests to control in industrial and residential areas and especially food processing facilities; but with the development of cockroach baits, these disgusting little nuisances were pushed off their pedestals, at least for some years. Humans lived without the fear of these pesky creatures for about a decade, but things have changed for the worst now. German cockroaches have taken their position as a top dog once again. So, following is a list of facts to help pest management specialists, as well as the public, learn more about why German roaches are such challenging, difficult to control invaders.
- Rate of Reproduction
A single pair of German roaches can turn into an infestation of more than a staggering ten thousand German cockroaches in a matter of months to a year. You can prevent this exponential population increase by making sure that control products like baits, sprays and other nonchemical treatments remain effective from one service to the other, or ensure that scheduled pest management services are frequent enough to outpace their growth rate.
- Protection mechanisms
German cockroaches prefer tight, hard to reach spaces like cracks and crevices where their back and their belly is able to touch at the same time, therefore detailed and thorough inspections are required throughout the house or building in which a roach infestation is suspected.
While German cockroaches can easily survive at normal temperatures and humidity, the ideal temperature for them to thrive is about 85° to 95° F along with 90 to 95% humidity in the air. In a building, German cockroaches are most likely to be found in places where the heat and percentage humidity are ideal. Look for them in places such as above refrigerators, warm pipes, inside the oven and stoves, and other appliances that put off heat and in places where moisture is present.
- Protected eggs
Female German cockroaches carry their eggs in an egg sac protruding out of the posterior ends of their bodies and drop it just before the eggs hatch. Sometimes the nymphs will hatch when the egg sac is still attached to the female’s body. During this time, the females will stay hidden in deep crevices cracks and protected voids, so make sure that you apply insecticides deep into these hidden areas and follow up with pesticide treatments no late than a month’s gap in order to control the spread of newly hatching nymphs.
- Resistance in eggs
German cockroaches lay eggs that are resistant to insecticides, because of the hard, protective egg sacs they are stored onto. Follow-up treatments are therefore necessary to eliminate the newly emerged nymphs.
- Resistance to insecticides
Developing a physiological or behavioral resistance against an insecticide is common for German roaches. A solution to counteract resistance is to periodically change the insecticides you are using for the elimination of these pests.
Finding all locations of aggregation is of utmost importance. If you happen to miss even one of them, an infestation is bound to happen once again and this time with an even greater force because the roaches will be resistant to all the prior insecticides you have used.
Dispersal is often observed when a treatment is applied. Make sure to treat all the rooms above, below, and adjacent to the infested areas.
- Threat avoidance
Insecticides will act as repellents at first, driving the roaches away before lethal dose levels. However, if the product is applied deep into the crevices and all the protectives voids in the building, the fleeing roaches would be unable to find a safe place to hide.
Upon perceiving a threat, German cockroaches will act accordingly by changing the place where they have been aggregating. Hence don’t make the mistake of focusing the treatment only on the apparent troubles.
We hate to tell you the bad news, but roaches actually do bite, especially the German cockroaches. They have been infamous for biting the flesh of human beings. They may bite on any part of the body, but they’re more likely to nibble on your eyelashes, hair or nails. German roaches are also known to bite pets like dogs and cats in your house.
If you happen to be shaking in fear at the thought of being devoured by roaches while you are sound asleep, take a deep breath because roaches are rarely known to bite because humans are their last resort. If there’s any sort of food elsewhere, these pesky nuisances will go ear that first.
The only time roaches are extremely likely to bite is when their population grows out of control i.e. your house has a very heavy infestation problem and the food resources are extremely limited.
Cockroach bite symptoms
You feel an itch and swelling on a body part of yours and it comes to your mind that you might have been bitten by a German roach, however you’re not completely sure. Following are some of the most common symptoms that are usually associated with roach bites.
A red bump like structure at the affected area. A roach bite is most likely to leave behind a swollen red bump, similar to what you would get when a mosquito bites.
Roach bites are known to cause redness and dermal rashes, especially if you happen to be allergic to these insects.
- A cluster of bumps
A cluster of bumps might appear at the affected area, although not as common.
The Appearance of Cockroach Bites
Roach bites tend to look very much like mosquito bites, but they happen to be larger in size and can tend to form scabs. Some people happen to get a cluster of bumps at the affected area, but this isn’t very common.
People allergic to roaches tend to have an even stronger allergic reaction. The bite would be even larger in size or it may swell up. A rash would also accompany the roach bite, which would make the skin appear further red and bumpy, and severe itching would be experienced.
When the roaches happen to bite sensitive areas such as the eyes, swelling is bound to occur. It is surprising that German roaches can even bite the eyelid while trying to nibble on your eyelashes. But then again, this is an uncommon scenario. These types of bites are commonly observed in children who might sleep on the floor or go into areas where the roaches seem to be hiding out.
If you’re still not sure whether the strange red bump on your body is caused by a German roach, you can look for roach bite pictures online, but it is ideal to consult a physician.
Treating Roach Bites
If you happen to get bit by a German roach, there is no need to panic. You must be wondering how to treat the affected area. Roach bites should be treated in the same way you would treat any other dermal wound and as always, usually, the first step is to clean it.
- Clean the wound
The simplest, easiest yet the most effective way to clean the wound is to dip a cotton ball (or a cloth in case cotton is not available) in rubbing alcohol and then gently apply the alcohol to the wound. Avoid scrubbing or harshly rubbing the area as it can lead to further inflammation.
Other antiseptics can be used if your skin happens to be too sensitive to alcohol. These include:
- Tea tree oil
Make sure that you dilute the tea tree oil with a carrier essential oil, like apricot, almond, olive or coconut oil
- Witch hazel
Witch hazel is an extremely soothing antiseptic agent
- Applying products to reduce redness and inflammation
Once you clean the wound, you can apply different anti-inflammatory products that will help fight inflammation as well as itching. Roach bites can be extremely itchy, but it’s important to resist the urge to scratch them. This is because our nails can easily cut through the damaged skin, which can lead to a deeper skin infection and lead to even more swelling and irritation.
Following are some ways to bring down the swelling and soothe the affected area:
- Applying an ice pack to the inflamed area. The cool sensation will help in bringing down the inflammation and numb the itchy skin to reduce that sting.
- Applying diluted lavender oil to the bitten skin. Lavender helps soothes inflammation and redness along with the itching, and also helps to keep the wound free of pathogens.
- Using a baking soda paste to reduce itching. Mix baking soda with a few drops of distilled water to make an even paste. Then apply this paste to the affected area.
- You can also try applying Aloe vera gel to the wound to keep it clean. Also, it has excellent natural anti-inflammatory and healing properties which also prevent itching.
- Keeping a close eye on the bite
It is important to keep a close eye on the bite and to keep checking it every now and then to check for immediate signs of infection. Following are some of the most common signs of infection:
- Swollen skin glands
- Pus present around or inside the bitten area
- Redness, inflammation, and itching in the bite area
If you happen to observe any of the above signs of infection, it is advised to see your doctor immediately. Your physician will be the most suitable person to prescribe an appropriate treatment to halt the infection.
Roach bites will typically clear up on their own in a couple of days without requiring any special treatment. However, it’s still extremely important to be careful and to make sure that the bite doesn’t get infected, which is a common issue in the case of younger children.
Roach Bite on the Eyelid
Although German cockroaches can bite on any part of the body they are more likely to nibble on your hair, nails, and eyelids. A bite on the eyelid is an even worrisome matter because eyes happen to be a very sensitive area and can become easily infected. Therefore, do not try treatments on your own using the above-mentioned products on your eye as it can further complicate the infection, and make an appointment right away to consult your physician. The doctor will then recommend the best suitable treatment with medicated ointments or eye drops.
Although cockroach bites are not something to be too much worried about, cleaning the wound right away and then keeping it clean at all time is of utmost importance. As discussed earlier, the body of these pesky invaders harbors a number of dangerous life-threatening pathogens, because German roaches scuttle through all sorts of dirty places like gutters, sewers, bathrooms, etc. and feast on excrement. Thus a bite can deposit all the bacteria they carry into the wound which can result in disease. It is important to not let the wound get further infected especially in toddlers.
Preventing an Infestation
Although German cockroaches are pesky dwellers which can creep inside your house through a number of ways, their presence is mostly linked to unsanitary conditions since these creatures thrive in the dirt. Following are a few simple yet effective steps you can take to protect an infestation.
- Ensure a clean and dry environment
Since German cockroaches mostly thrive in kitchen and bathroom areas, eliminating moisture and food scrapings and storing your soapy products out of their reach will limit their growth and survival. It is also important to fix any leaking pipes and don’t let water accumulate in an area.
- Emptying pet food containers
It’s highly likely for the roaches to feed on your pet’s food unless you properly remove it. Clean your pet’s food bowl thoroughly and make sure they are dry before going to sleep every night.
- Using a dehumidifier
Since roaches thrive in hot and humid environments, thus using a dehumidifier is an efficient way to drive them out to look for a more humid place to survive in.
- Maintenance of clean kitchen cabinets
Your trash is a feast for German roaches! Even the smallest of the food scrapings can drive a dirty cockroach in your kitchen. Therefore, make sure that you thoroughly clean your cabinets on at least a monthly basis to deprive these pests of food sources. Also, clean the dirty dishes immediately and don’t leave them in the sink overnight.
- Proper trash management
Cockroaches love feasting on trash, so avoid leaving it out in the open for them to feed on. Also, make sure that all of your trash cans are tightly sealed so that these filth roaches don’t end up sneaking into them.
- Sealing food containers
Make it a habit of storing food in tightly sealed plastic containers. That way you can ensure that no pests gain access to your food.
- Ensure dryness
Take some time to dry all the sinks, showers, and bathtubs in your bathroom because doing so you ensure that the roaches are deprived of a moist environment to thrive in.
- Sealing cracks
Since these urban invaders are very tiny therefore they can easily enter your house through tiny cracks and crevices and then hide there to reproduce. Therefore, sealing these cracks and voids is very important to prevent an infestation.
- Checking secondhand goods
Before buying secondhand appliances, furniture, bedding, carpets or other goods, thoroughly check for the presence of German roaches since these pesky invaders can easily hitchhike thorough these items into your house and create a nuisance.
German cockroaches are small pesky nuisances which can be difficult to detect because of their size and nocturnal nature. Because they avoid cooler temperatures, they are an indoor pest. Following are some signs your house might have a roach infestation:
- Daytime activity
They are nocturnal pests therefore if you happen to see a German roach scuttling across the floor during the daytime, it can be a sign that your house might be a victim of heavy infestation.
- Foul odor
As mentioned above these roaches generate a foul smell, therefore a musty odor is an indication of a heavy infestation.
The gross roach droppings are easy to identify on kitchen counters and in the corners of the rooms as they appear like ground pepper or coffee grounds which stain the surface they are present on.
- Corpses and casts
The presence of dead roaches, their skin casts and egg capsules released from the female roach’s body are a clear sign of infestation.
- Nighttime activity
Leave the kitchen or the bathroom area dark during the nighttime for about an hour or two and then lighten it up and you are likely to find a cluster of these roaches particularly in these places because they happen to be damp and moist and offer plenty of food to the pests (food scrapings and soap, etc.).
Effective control of German roaches is comparatively easier in temperate climates where the cockroach populations are unable to survive outdoors in winters, than in warm, humid regions. The first step towards control is maintaining cleanliness, which is relatively difficult in houses where there are children and pets. In isolated houses, control is easier to achieve as compared to apartments where roaches have easier access from adjacent houses. Reinfestation can occur from outdoors in warmer areas, in heating ducts and pipes in apartments, or from grocery bags, luggage or second-hand items brought from the cockroach infested places.
Cockroaches can even be found in immaculately clean houses, but over there they are rather unlikely to establish colonies. Presence of several sizes of nymphs and egg cases is a sign of a well-established colony. Heavy cockroach infestations can be treated using chemical control measures, along with environmental management to restrict the access of these pests to food and shelter. Smaller populations can be easily controlled using baits and traps.
German cockroaches are rather difficult to control using insecticides for many reasons, one of which being that they might become resistant to commonly used products. Most insecticides act as repellents to them and are therefore avoided. Chemical control only gives temporary relief and for permanent removal of roaches, it should be accompanied by improving the cleanliness conditions of your residence.
Insecticides are applied to the hiding places of cockroaches as residual sprays along with insecticidal dust. Such applications tend to be effective for time periods ranging from many days to months, depending on the type of insecticide and the surface on which it is applied. Insecticides are often combined with attractants such as toxic baits.
The German cockroaches are unfortunately resistant to several insecticides containing the compounds organochlorine, organophosphorus, carbamate and pyrethroid. Oriental cockroach, the American cockroach, and the typical large brown cockroach have developed a smaller scale resistance, mainly to DDT and chlordane compounds. Recently, the American cockroach has been observed to show resistance to trichlorfon products in China and the large brown cockroach to diazinon products in the USA. Areas that should be thoroughly treated include kitchen, washrooms, in and around the sinks, in or under the cupboards, under furniture, near refrigerators, ice boxes, and other water structures, in cracks and crevices, food preparation facilities, ducts, pipes, and sewers.
Frequency of Treatment
A number of factors govern how long the insecticide deposits remain effective for example how thoroughly the treatment has been applied, the frequency of re-infestation, the nature of the chemical used, the dosage and product used, type of substrate to which it is applied, temperature and percentage humidity. Insecticides tend to last longer on painted as compared to unpainted surfaces and last longer on wood as compared to brick surfaces. Frequently washing the treated surface as well as dust or grease render an insecticide ineffective. A single treatment rarely results in the eradication. For most species of pesky roaches, additional treatments might be necessary on a monthly basis in order to kill newly emerging nymphs and to prevent the recurrence of infestation.
Proper care should be taken to avoid contamination of food products. Avoid treating the areas where there is a chance of toddlers coming in contact with the residue. In special cases, such as while treating zoos or pet shops, residual sprays or dust should better not be used. In such situations, it is better to apply a limited amount of chemical product with a brush. Alternatively, a chemical product which is of low toxicity to mammals and avians e.g. boric acid powder or silica gel can be used. Some formulations have the ability to stain clothing, wallpaper, floor tiles, and other household items. Thus all such information about the nature of products should be collected prior to the treatment.
These are usually applied with plunger-type sprayers or hand compression air sprayers. The sprayers have pin stream nozzles to spray the insecticide deep into cracks and crevices and areas that are hard to access. A broader fan spray is used for areas that are more reachable. The spray should be able to moisten the surface thoroughly but not to the point that it starts dripping or running off. About four liters of diluted insecticide per each 100 square meters area is rendered appropriate. The insecticide can also be applied using a paintbrush in case of unavailability other equipment. Properly treating runways and harborage areas is very important for significant control of the pest population. Initially, a heavy treatment is carried out followed by follow-up treatments of periodic nature.
Because of the roaches developing resistance and for environmental safety purposes, the chlorinated hydrocarbons have been replaced by the biodegradable organophosphorus and carbamate ones, synthetic pyrethroids and more recently by the insect growth regulators. Insect growth regulators are compounds highly toxic to the insect larvae or nymphs, interfering with their morphogenesis into adults. The good thing is that they have negligible toxicity towards non-target organisms. However their use is limited because of their high cost and unavailability in many places, but they are of considerable value particularly where cockroaches have developed resistance to other insecticides compounds.
Formulations of dry powder are made by mixing the insecticide powder with talcum or some other inert carrier which is powdery in nature. They come in handy while treating hollow walls, voids, false ceilings and other places these pesky crawlers hide and which are hard to reach. The powders can be blown into spaces using a plunger type duster or can be applied using a spoon. Slender extension tubes can be attached to a duster to blow the dust deep into the roach hiding places. The dust disperses very well and has the ability to penetrate deep into the cracks and crevices. But be careful that heavy dust deposits might repel or drive away roaches and lead them to migrate to untreated or less accessible areas. Dust should also not be applied to wetter surfaces as this renders them ineffective. When used along with residual sprays, dust should be applied once the sprayed surfaces become dry.
Insecticidal aerosols are very fine sprays of small droplets of the insecticide. Aerosols are not effective for residual treatment, but they can be employed for space spraying because the droplets tend to remain in the air for a long time, consequently killing pests by contact. Aerosol spray cans containing a residual insecticide along with a knockdown insecticide (such as propoxur plus a pyrethroid) are especially suitable for cockroach control and are also widely available. Aerosols can penetrate into narrow crevices and other inaccessible pest hiding places. The compounds they contain and other irritants tend to drive the roaches out of their hiding places, ultimately shortening the time of kill. Aerosol application results in a quick reduction in cockroach populations, however in order to maintain long-lasting control, follow-up treatments with a residual spray is necessary. Cities or large industrial areas sometimes control cockroach populations on a large scale with the help of fogs generated by thermofogging machines.
Clouds of insecticide particles produced by heat are known as smokes. The particle size happens to be even smaller than in aerosols. Smokes penetrate even deeper into hiding places and crevices, being particularly useful in basements, sewers and drainage systems.
Baits have been used since ancient times for cockroach control and are still used in certain situations, such as offices, laboratories, and residential areas especially if the pests have developed resistance to some of the common insecticides used. Commercially available control products work by attracting cockroaches to a specific area and then trapping and eventually killing them over there. Substances commonly used as attractants are food items, pheromones (aromatic compounds) and other attractant chemicals. The trapping element can be a mechanical trap or some sticky material. You can also construct a jar trap using an empty jar, petroleum jelly and some kind of food product. The roaches are attracted to the jar by grains, raisins or any other food item placed at the bottom, and a thin layer of petroleum jelly applied on the inside rim of the jar prevents the pests from escaping.
Toxic baits are generally used without a trapping apparatus. They are made up of a mixture of attractive food items and an insecticide. Several types of bait are available in the market as pellets, pastes and even gels.
Some excellent type of gel bait products commercially available is the Alpine Cockroach Gel Bait and the Advion Cockroach Gel Bait insecticide. Both of them are extremely effective both efficacy and spectrum wise i.e. the pests are very unlikely to develop a resistance against it. These products have been used by many people and they are extremely satisfied with the results.
Pellets are dispensed in containers or scattered in narrow concealed places. Pastes can also be used in a similar manner. Some of the recent formulations are dry by themselves and can be directly applied to various surfaces. In a few countries, dry baits are commercially available in sealed traps which are safer to use in residential areas in the presence of children or pets. Some of the food items which can be used in the baits the roaches are particularly attracted to peanut butter, pet food, and maltose.
Baits and traps are easier to use and should be placed in areas frequently visited by the roaches. They are even more effective in places where there is a very to compete with the bait, such as in offices and laboratories. Maintaining a hygienic environment is equally important when baits are being used alone. In the areas heavily interested, baits need to be frequently replaced.
The use of repellents for the control of roach populations is of emerging interest. They are of special interest for application in shipping containers, and in boxes containing food items, beverages, and other stuff. Keeping the pesky roaches away from these places prevents the spread of these crawlers from one region to another. Repellents can also be used in kitchen cabinets, vending machines, and other places where food and beverages are stored. Essential oils such as mint oil, lemongrass oil, spearmint, and eucalyptus oil are known to have roach repellent properties, but best results are obtained using synthetic products that are easier to standardize e.g. packing materials and insides of boxes treated with chemical dilutions.