The least loved of all animal species are those that end up as urban pests, such as cockroaches.
Cockroaches can be considered living fossils, since they have been on Earth for 300 million years and have a very similar appearance to that of their ancestors. Some 3500 species have been identified, most of which have a tropical origin and live out of doors. In their original ecosystems they carry out basic functions such as decomposing organic matter and serving as food to superior species. They are very adaptable, which has allowed them to colonize our cities. They have proliferated so much that they have become parasites for us, so successfully that getting rid of them is proving to be very difficult. A cockroach was captured inside the Apollo XII space capsule on its return to Earth from the Moon, which gives us an idea of how adaptable they are and how they are able to spread.
Only three species invade Spanish homes: the American or flying cockroach that has a brownish-red colour and is almost four centimetres long; the German cockroach, which is the smallest at one and a half centimetres and the most widely distributed through premises such as restaurants and warehouses; and the Oriental cockroach, of a dark coffee colour and intermediate size. Oddly, some exotic species are sold as pets. For example, the Madagascar cockroach, much larger than the cockroaches mentioned above, is called the “hisser” because of the sound it makes when it mates and when it feels endangered.
These insects are very resistant, even to radiation, to the point where a cockroach was the first animal that was found without having suffered any apparent damage after the nuclear explosion on the Moruroa atoll. Cockroaches are nocturnal and live in groups. They need heat, moisture, food and shelter to survive. The two first conditions determine their life enormously. During the cold months the proportion of adults is lower and they are not very active, but during the warmer months their number increases substantially.
Cockroaches are able to eat adhesives, resins, decayed substances, clothes, hair, leather and paper, but they are especially attracted to food scraps. They are able to feed practically on any kind of material or element available to them. Adults may live up to a month without water and two months without food. Their capacity for survival is amazing. They have been on Earth much longer than human beings, and will probably remain when our species disappears.
One of the hazards of cockroaches is passive transportation and spreading of disease-causing germs that they acquire by coming into contact with contaminated materials. Salmonella strains have even been found on cockroach trails. Their digestive tracts may contain different infectious agents that they eliminate through their faeces, which then become new bearers of pathogens. On the other hand, cockroaches are one of the most frequent causes of allergic asthma.
Besides these health risks, they also have against them the generalized repulsion they provoke in most people. This is why so much effort is put into getting rid of them by individuals as well as by local authorities, which carry out eradication campaigns in the sewer systems. But large-scale eradication campaigns have always been ineffectual because the places that have been treated are re-colonized by individuals from untreated areas.
Campaigns against cockroaches must always combine control measures with preventive measures. Control measures may include pesticides and adhesive traps containing hormone or food bait. But cockroaches are so resistant to pesticide treatments that the attack cannot be based solely on chemical warfare, although, if used, chemical products should be rotated. If you must use insecticides you should never apply products that are not allowed for domestic use and carefully read the labels before using them. Keep the containers out of the reach of children, and never put the contents inside other containers to avoid their being confused with food.
As to preventive measures, they are vital to avoid re-infestation. The most critical one is blocking cockroaches from access by sealing cracks, holes and air chambers, and protecting hatches, drains and gratings. Avoid having areas where moisture or water can accumulate, seal rubbish containers and get rid of food scraps. Food should be stored so that it is not accessible, and kitchens, bathrooms and toilets should be cleaned thoroughly. Although eradicating cockroaches seems almost Utopian, these measures make it possible to get rid of them in a specific place such as your home or business premises.
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