Prof. Ignatowicz on the cockroach: an insect that carries eggs in a pouch

There are three species of cockroaches in Poland: the German cockroach, the Oriental cockroach, and the American cockroach, and it was we, Europeans, who brought this species to the United States, not the other way around.

The cockchafer is a common sight in our apartments. In an apartment building, it can inhabit all floors.

– And it is considered by many to be the ugliest animal under the sun, almost everyone is disgusted by it – pointed out the entomologist.

He added that the cockroach, like other cockroaches, "carries a wide variety of pathogens – viruses, bacteria, protozoa, and even parasites" – more than 50 pathogens in total.

– He contaminates food products with them, and we become infected by eating the food he shares with us – explained the scientist.

He emphasized that every cockroach eats whatever it likes, "and it likes almost everything," and therefore it occurs wherever there is food, even its crumbs - not only in kitchens, but also in living rooms, bedrooms, and even bathrooms - "everywhere we walk and snack."

Moreover, as Professor Stanisław Ignatowicz emphasized, this insect is very resistant to hunger, it can survive up to a month without food, but thirst is particularly bad for it – "it cannot survive without water for more than 7-10 days."

The entomologist explained that he sometimes asks his students a tricky question: what happens if you cut off a cockroach's head? There are three possible answers: it will walk around in circles because it doesn't know where to go; it will be unharmed; and it will die of thirst after a week.

– This third answer is correct – he said.

He explained that the cockroach has so-called pads on its paws and appropriately developed claws, thanks to which it can move even on smooth, vertical surfaces.

– Its relative, called the Oriental cockroach, does not have such suckers and is quite heavy, so it most often inhabits ground-floor rooms, e.g. confectioneries or bakeries – pointed out the professor.

The Oriental cockroach can be found on upper floors, but only if it is dragged there – then it will not inhabit the building evenly.

Both species have a penchant for gregarious living. "Their offspring develop and grow much faster when kept in groups than when kept alone," noted Professor Ignatowicz.

He explained that males and females deposit their feces in one place, along with the so-called aggregation pheromone, which seems to call out to other individuals: "Come here, everyone, it's good and safe here!"

– The toilet is also a safe place for humans, if I remember correctly, only in the movie "The Godfather" someone is killed in this room – the scientist joked, and then explained that it is similar in the case of cockroaches.

He pointed out that the insects living in the colony share responsibilities. "The strongest and most experienced individuals go for food, while females, for example, who have laid just over 30 eggs in their so-called ootheca, stay put to avoid exposure, because it's very dangerous outside, and they need to protect their young," he said.

"They come out when they have no choice and are really hungry," Ignatowicz explained. Interestingly, he added that "the female must lay a sufficiently large number of eggs from which young larvae will hatch, so that when they inhale air, they will press against the walls of the sac so hard that it bursts." If there are too few eggs, the larvae will not generate enough pressure and will die in the sac, never reaching adulthood.

“Males and females without pouches, i.e. not yet fertilized, bring more food than they need and share it with their colony mates, which is called trophallaxis,” the scientist said.

People exploit this tendency to share cockroach food to control them. Professor Ignatowicz reported that "very tasty gel preparations have been developed," which are then applied in droplets to the paths frequented by these insects.

– The food gatherer comes, eats, takes the rest to the colony and feeds his colleagues there – he described.

The insects feel unwell and vomit, and others consume the vomit, thus introducing the poison into their bodies. He added that the weakest die first, and then the stronger ones consume their bodies, because "in a cockroach colony, nothing can go to waste."

– This is the best method of combating these insects – emphasized the entomologist.

The third species of cockroach living in Poland is the American cockroach, which is the largest of them and can fly, "flying, for example, from the balcony of one apartment building to another." In contrast, the German cockroach "uses its wings like a paraglider to land softly," while the Oriental cockroach has only wing buds, "more of a decoration, because it is ponderous and incapable of flight."

Prof. Stanisław Ignatowicz warned that everything indicates that the three species of our native cockroaches will soon be joined by a fourth – Supella longipalpa, also known as the brown-striped cockroach or streaked cockroach – it can fly quite well and, moreover, moves very quickly, even for a cockroach, especially on walls and ceilings.

Moreover, unlike its cousins, it prefers warm, dry places and is not bothered by sunlight. It carries the same pathogens as they do, and its secretions can also cause allergies or asthma, especially in children, and it is very difficult to eradicate.

– Supella is already in Italy and southern Germany, so we can expect that with the warming of the climate it will also reach us – noted Ignatowicz and mentioned that there was already a case in Poland when tourists from warmer countries brought this insect to a rental apartment in Krakow and “our specialists fought it with great commitment.”

The entomologist explained that most cockroaches lead a lifestyle similar to that of a mouse or rat.

"When the sun goes down, they become active because they are hungry, and they stay in their hiding places all day, so we don't always realize quickly that we have roommates," he said.

However, if we enter the kitchen at night and turn on the light, there's a good chance we'll see them fleeing, frightened by the light and the air movement they detect with their hair-covered appendages. A fleeing cockroach can change direction 25 times in a single second.

Unfortunately for us, cockroaches also emit an odor that, according to an entomologist, resembles that emitted "by rotting organic matter."

However, as it turns out, not everywhere in the world people have such a negative attitude towards cockroaches as we do. Professor Ignatowicz reported that in Jamaica, for example, cockroaches, the size of an adult man's hand, are a delicacy and that local housewives prepare them for honored guests, while in Zimbabwe, beer is made from the very smelly bugs.

Mira Suchodolska (PAP)

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