Some cockroaches from tropical countries can reach an imposing size; they often appear in horror films or endurance tests because of this characteristic. The German cockroach is the variety most commonly found in households throughout Canada, and one of the smallest (1.0 to 1.5 cm). It can be distinguished by two lines, parallel to its body, on the rigid part that covers its head. This “hidden” head is a particularity common to all cockroaches. The species that live indoors have varying color patterns, but they are often brownish. Their bodies are oval and they have long antennae. The adults have wings that are shorter among some species, especially on the females.
There is over 4,000 different species of cockroaches in the world, most of which live outdoors. They recycle matter (animal or vegetable) by eating it and in turn becoming food for other animals, and they pollinate plants as well. Only a few species invade houses where they proliferate, often because they are an exotic species and their natural enemies did not follow them.
Their eggs (about 30 for the German cockroach) are enclosed in a capsule called an ootheca or egg case. The female will produce several in her lifetime. The ootheca can initially be transported inside the rear part of the female’s body and then left in a place where the little larva – miniature adults – will emerge. As they develop, the wings of these young ones will become as long as those of the adults who sometimes use them to glide.
Cockroaches communicate chemically using pheromones – substances they secrete and can smell – for example, to guide them toward sources of food discovered by fellow cockroaches. An aggregation pheromone marks the place where they congregate. The hairs covering appendages on the back of their bodies are sensitive to air movements, which mean they are quickly alerted to our presence and can move very fast. They become more active at the approach of nightfall and flee the light. During the day, they can only be seen when population numbers are high. They can invade other nearby locations in no time at all.
Places where they can be found in the home
Cockroaches are attracted by foodstuffs we leave lying about and are therefore often found in the kitchen, but also in the bathroom since they need moisture and water. The different species do not necessarily seek the same habitat. Some live in drains, sewers, furniture, under the refrigerator or oven, near hot pipes, in cabinets, drawers and pantries, amongst other.
German cockroaches prefer sweet substances, but if they are hungry, they will even eat the glue used to bind books. They contaminate food by leaving behind their saliva and excrement. These foul-smelling brown castings are a clue to their presence.
When you come back from the grocery store, examine your bags carefully. Paper bags provide an ideal hiding place. Changes you can make to your environment (explained in the following section) are measures that dissuade these insects from setting up house in your home.
Cockroaches seek what they would find in their natural habitat – warmth, moisture, water, food and small places where they can feel safe. Even if an insecticide effective against these insects were sprayed everywhere in a building, it could not prevent new cockroaches from setting up shop later if they found what they needed. Insecticides only treat the symptoms, not the cause of an infestation. It is much better to modify the habitat to make it less favourable to their survival. The German cockroach will not survive very long if it does not have access to food, and even less longer if deprived of water or moisture. It is therefore essential to make sure that no water is accessible by repairing pipes or faucets that leak and by finding a way to provide drinking water to pets but not cockroaches. Try to control moisture by de-humidifying or ventilating rooms. Also, it is advisable to wipe down or insulate pipes that are covered with condensation.
It is also necessary to organize elaborate management of foodstuffs, crumbs and scraps to ensure they are not within reach of cockroaches, especially around a source of moisture that cannot be eliminated. Food should be kept in hermetically sealed containers. Dishes that cannot be washed immediately should be left in a tub of soapy water. Bottles and cans intended for recycling should be washed so that no residue is accessible. Keep a tight-fitting cover on your small indoor plastic trash can and the outdoor one. Look for cooking grease that accumulates around the oven as well.
Cardboard sticky traps (to which bait or pheromones are sometimes added) should be placed along walls on paths the cockroaches use in their search for food and water. More of them can be captured near areas where they hide in groups. All the small cracks that provide potential hiding places near these areas should be filled in or plugged. Small screens (or draft guards under doors) should be installed to prevent cockroaches from intruding and spreading out between apartments. It is also worth taking the time to explain the importance of such measures to everyone living in the infested house or building. It should be well understood that the problem cannot be solved by moving, since it is easy to take them with you in your baggage. You can check whether fewer are being captured by placing new sticky traps. You should be aware that, in most instances, the use of sticky traps will not be enough to control the number of cockroaches if not done in conjunction with some of the previously mentioned measures.
It is better not to spray just any old insecticide around indiscriminately, since cockroaches rarely move about in the open, and the odour of a poorly chosen product can drive cockroaches into hiding places that they will leave after waiting a bit. It is also important to prevent cockroaches from becoming resistant to the insecticide which would then become ineffective against them. You should also know that just because an aerosol product is well known and readily available does not mean it is harmless to humans if abused in one’s home. Some pesticides can make the cockroaches that have been sprayed leave quickly but without solving the problem. When you plan on using an insecticide, make sure it is recognized as effective against this type of insect, and that its toxicity is as low as possible to humans (who will have to abide by the amount of time they cannot remain indoors, if applicable). An effective poison, applied only in areas where necessary, sometimes gives good results when it is ingested by the cockroach. The insect’s protective layer will be scratched if it rubs against a diatomaceous earth (silica compound) based powder along its route or in its hiding place. It will then die of dehydration. Products of this type, prepared from natural elements, are sometimes combined with other chemicals. Since cockroach problems occur all around the world, there is a wide range of product choices. Soil micro-organisms, chemicals that prevent larvae from developing, various baits, insecticides that act on contact with the insect, and combinations of these products with aggregation pheromone are used.
Some people are allergic to cockroach excrement, exuviae (old skins) or substances left behind that can become suspended in the air. They develop a variety of symptoms that could result in asthma or, rarely, more serious complications.
While it can be terribly upsetting to realize that our home is invaded by cockroaches, we should never subscribe to the widespread false belief that their presence is the result of poor hygiene. Since cockroaches are famous for liking small thin cracks where they can feel safe, and because they spend 75% of their time at rest, it is very easy to bring them into your home in the fold of a paper grocery bag or in the corrugated cardboard of a box. Furthermore, since insects of all sorts are omnipresent in our surroundings, it is best to try not to make our home too comfortable by leaving food within their reach.
Contrary to what people might think, cockroaches spend a lot of time cleaning their bodies to ensure that the sensorial hairs that cover them will be fully functional, and it is in this manner, among others, that poisons can be ingested and become effective.
Other interesting facts
Man exploits cockroaches for several purposes, as laboratory animals or pets, or for their medicinal properties. They even seem to have some ability to predict earthquakes. As early as 1996, one species was protected by a Porto Rican law on endangered species.