German Cockroach appeared on earth way before humans or any other current organism did, more than 300 million years ago, even though the present-day cockroaches that we come across today have evolved with time and differ from their ancestors in several terms. Though small, they are still, one of the most populous organisms and can be found across the globe. Ranging from different sizes and different colors they are spread around the world in all kinds of ‘nests’ where to keep existing even today. Forests, to industrial cities and towns; all have at least one or the other kind of cockroach inhabiting their trees and lanes and pipelines.
Like any other line of organisms, they have different kinds of lineage dividing the larger order Blattodea into smaller families and species. Quite interestingly, termites while belonging to this order, run parallel to the cockroach variety and were previously considered very different from them.
There are a little less than 4700 species of cockroach known yet, out of which 28 to 31 are found in surrounding man and very few are established as pests.
German cockroaches are unique in the sense that they probably grow the fastest, each adult reproducing generations of nymphs, and eventually adults, that continue the cycle and populate their area of ingestion quite densely.
The scientific association of the German Cockroach:
The German Cockroach belongs to the genus Blattella and species germanica that and hence is scientifically known as Blattella germanica.
It comes from the superorder Dictyoptera and more specifically the Ectobiidea family.
They are Arthropods, because of the presence of an outer harder and solid skeleton-like structure that gives shape to their body, which is divided into segments, belonging to the phylum Insecta and runs parallel to the order belonging to other insects like a mantis.
While other insects like butterflies and moths too belong to the same phylum, cockroaches differ from them point down which is categorized as one goes down the scientific nomenclature system classifying the organism into its specific and objective category.
What does a German Cockroach look like?
A German Cockroach is considerably small in size when compared to its other variants. The dimensions of an adult German Cockroach are about 1.2cm to 1.7cm approximately or 0.42 inches to 0.61 inches approximately.
They are burnt brownish to a very deep brown that often seems black. However, the characteristic feature of this type of cockroach is the dual lines running from their head right to the base of their wings which is the spot from where the structure for their wings begins.
German cockroaches may have wings. However, unlike their other varieties, for example, the American Cockroach, they cannot fly. Though they have been seen to be doing a pseudo-flight movement, however, they can hover around but not fly completely.
This type of cockroach can be easily confused with the Asian Cockroach because of its size and color. However, one needs to look closely to distinguish between the two by the dark lines running on their anterior section of the head.
The male and female German Cockroach can also be distinguished. The male German Cockroach is slender and not exactly thick, with a sharp body and its segmented posterior section visible. When looked at from a distance, the name seems a little lighter in color than the female probably due to the structure of the density of the wing and abdomen. The female is rounder to look at, with a denser color around the abdomen and is more stalky than sleek. It has tegmina, the leathery wing which covers most of its body, and hence its segmented structure is usually not visible.
Where did the German Cockroach originate?
As the name itself suggests, it was thought to have belonged to European countries. However, its origin was later tracked down to other locations after considering other factors and characteristics it exhibits even today. People believed that the German Cockroach might have originated from parts of North-East African nations. However, it was later confirmed that this variant was in fact, first found in countries like now Thailand, in South-East Asian nations.
This confusion over their origin in ‘Germany’ or any other European nation was because these cockroaches can hardly tolerate lower temperatures and thus might have originated somewhere warm and damp, like their habitat preference till today. This is also a viable reason that explains their absence in the polar regions which are extremely cold with little to no food supply and other remote yet big lands detached from the rest of the larger pieces of landmasses that are otherwise interconnected. While the cause for their situation to warmer climates can be understood, the spread across the globe probably traveled across the seas in larger carriers like ships.
Where can the German Cockroach be found?
The German Cockroach can be found in warm and damp habitats and are most common in residential apartments and blocks, all sorts of kitchens be it domestic or commercial, other organizational buildings that are inhabited by humans. This is because any human habitations are usually warm and suit the German Cockroaches requirements better to build a nest and procreate. Since they are small, they tend to inhabit the cracks and spaces between furniture surfaces in warm places like the kitchen which serves to be the best location in terms of their temperature requirements and food availability. One can find a German Cockroach in a dark nook between items of furniture and the walls or in the deep dark crack of some surface, with their body inside and antenna outside, sensing any kind of movement that could be a potential danger to them, upon sensing which they immediately shutter deep inside their habitat. When frightened or caught by surprise, German Cockroaches tend to release a stench that acts as signifiers for their existence.
While they are nocturnal, and hence should stay inside during the day, they are often spotted even during the day time in the kitchen or other warm places of the house or building, especially if a light is suddenly flashed in a dark room.
German cockroaches have a strong affinity towards warm and damp places since they cannot tolerate cold temperatures. This is one of the most important criteria for them choosing to build their nests in human-inhabited buildings or other kinds of places where there is human interaction since it provides them with the warm atmosphere they require. The temperature range that a German Cockroach finds most suitable is around 60°F to 97°F which is about 16°C to 37°C. Any lower than the given temperature ranges they become unable to move and hence feed and if too cold, they cannot survive. They are most common in kitchens and food industries and factories which are heated and can be a source of food scrap for them to feed on.
If a building or house is uninhabited by humans for a long time, leaving the place cold and empty, these cockroaches tend to move away to more suitable locations.
What does a German Cockroach feed on?
A typical German Cockroach feeds on scraps of chicken, mutton, fish or any other meat available, food fats, sweet items, starch products like rice grains and in the absence of these, can switch to domestic everyday items like glue and book bindings, detergent, paste among other things. Surprisingly, if need be, a typical German Cockroach can change its food habits to become cannibalistic and feed on each other if there is an acute shortage of food and resources.
The lifecycle of a German Cockroach:
The lifecycle of a German Cockroach is like that of any other variant of cockroach, or insect in general which involves an egg stage, a nymph stage, and finally an adult stage.
During the egg stage, the mother cockroach carries the eggs in a pouch that remains attached to its body. Once the eggs are hatched, the nymphs start appearing and go through a period of transition that involves them shedding their cover and after multiple religions of this stage of coming out of their shell, they turn into adults. It takes about one and a half months to two whole months for a nymph to go through its mounting stages and turn into a mature adult. The adults then, further give birth to a new generation of nymphs, and the process repeats. The average time for which a German Cockroach lives and completes its life cycle is usually about 120 days, although a large part of it varies with the availability of food sources, shelter, and temperature conditions.
Reproductive Cycle of the German Cockroach:
It is to be noted that the reproductive cycle of the German Cockroach is very short and takes place very quickly, allowing each adult female to reproduce very fast and hence create a larger population of multiple generations very fast. Cockroaches release a sex pheromone which is known as Blattellaquinone that attracts a male cockroach towards the adult female.
The reproductive cycle starts once the female is fertilized and starts producing a pouch that is rectangular with rounded edges and about a quarter of an inch in size with ridges or segmented lines running across. This pouch is known as the Ootheca and holds the eggs (about 35 approximately) inside it and causes the body of the cockroach to seem fuller in size. As the pouch starts coming out of the posterior side of the adult female German Cockroach, it changes its color from pale to light red and funnily a deep reddish-brown. The eggs, which are usually fully developed, sometimes hatch out even while the pouch is attached to the female body. However, the rest of the nymphs are born only after the pouch drops off. The size of the nymphs is usually 2.9 mm although more than 50% of the nymphs die. An average German Cockroach usually undergoes rounds of ecdysis, the phase between each round known as an instar. It can be claimed that many nymphs never get past the instar phases.
Considering the rapid growth in their numbers once they turn into adults, it can be considered as a natural elimination or controlling process to keep their numbers at bay.
These nymphs usually have a deep-brownish tinge and lack wings, although they have chemoreceptors that enable them to sense any signs of chemical presence from a distance and hence are usually very difficult to poison with insecticides.
Pest control measures for German Cockroach :
German cockroaches can be considered kings among household pests because of their high rates of reproduction which often allows multiple generations to exist at the same time in the same location, infesting whole buildings at times. This can be supported by the fact that buildings infected by these pests have found hundreds and thousands of these pests in numbers, creating nests in hollow spaces across different areas of the building.
The presence of German Cockroaches is highly unhygienic because of the diseases and illnesses that they spread. As pests, they often play host-organism to other bacteria and viruses which can then spread through the food or items they excrete on. Their presence, while pointing towards unhygienic living conditions also indicate possible illnesses and problems that can spread among the people inhabiting such surroundings. The factors that render them a difficult variety to control are because of their small and unreachable nests, extremely vigorous reproductive cycle, the absence of any higher organism preying on them, and most importantly the ability to sense chemicals. German Cockroaches live in small cracks and corners and hence can be found in large numbers if one is found and the rest are searched properly.
Insecticides drive them away from specific locations although they can return to the treated surface once the effect of the chemical is gone. This suits them perfectly since they can sense chemicals and can afford to stay away from spaces that they sense have been sprayed with chemical compounds. On the other hand, since they inhabit small spaces, locating and eradicating all together is easier if their nest is found.
A common procedure of using glucose as bait for pests do not work on these cockroaches since they stay away from them, with time and adaptation. On the other hand, their reproduction rates are quickened if they manage to keep their temptation at bay, almost as a reward. Hence, the use of pest bait is also usually useless when it comes to these organisms.
The only option is to spray entire apartments, including the drains and pipelines along with all cracks, nooks, and crannies and the base of floorboards and other hollow surfaces through the building, where even one apartment is infected. This is because the German Cockroach tends to change its habitat now and then, and if it finds a location heavy with chemicals it moves to someplace nearby that is free of these toxins. After a while, they can move back to their previous habitat once the effect of the toxin is lost.
Pest glue traps can also be used to trap pests. However, the best way is to seal all gaps and hollow spaces, and regularly move items of furniture to clean spaces and keep a place neat and tidy. Also, periodic pest control checks and services are equally essential to keep these insects at bay.