- By Vil Malinoshevsky
- About cockroaches
Cockroach larvae are the most dangerous part of the entire population of cockroaches in an apartment for people.
Firstly, there are the most of them here and they are the ones who bring the largest amount of various contaminants into the room and onto food products in the room from sewers, garbage chutes, entrances and other less clean places in the house.
Secondly, it is the larvae of domestic cockroaches that are the source of strong allergens, due to which, perhaps, some of the people living in the house constantly have a stuffy nose and develop chronic allergic rhinitis. Young children are especially sensitive to these allergens - a significant part of children's runny noses, which are not accompanied by an increase in temperature, are caused by cockroach nymphs.
What kind of allergens are these and why are cockroach larvae more dangerous as carriers of allergens than adults?
What do eggs and egg capsules look like?
The first stage of cockroach development is the egg, in which the larva is formed. The eggs of the most common red cockroaches look like grains of rice. These are elongated, translucent, whitish formations, reaching a length of 1-1.5 mm. Using a magnifying glass, you can see a darkening inside the egg - this is a developing embryo.
An ootheca forms in the female's body shortly after fertilization. The material for its creation is a sticky secretion secreted by a special organ that every female has. The secretion quickly hardens, so that the walls of the ootheca become excellent protection for future offspring.
Cockroach eggs
The egg capsule has an elongated shape with slightly rounded corners. Its color varies from beige to dark brown, and its size depends on the type of insect. The ootheca has raised walls; the surface above each egg is slightly convex.
Photo
In the photo below you can see the appearance of cockroaches at different stages of development:
In the photo: a pregnant cockroach
This photo shows cockroach eggs:
Here is a photo of a cockroach larva:
And below you can see a photo of a baby cockroach, the so-called nymph:
The birth process of cockroaches
The process of birth of larvae is the same for all representatives of the cockroach order; it differs only in details. Thus, the female black cockroach sheds the capsule soon after its formation, which negatively affects the survival of the larvae.
Prussians are much more careful about their offspring. The female carries the ootheca until the moment when the nymphs are ready to be born, and only after that leaves it in a secluded place.
And a pregnant female Madagascar cockroach carries a capsule with eggs in her abdomen just before the babies are born, and they hatch from the eggs right in the mother's body.
By the time the larvae are born, the walls of the ootheca dry out and become thinner, so that it is not difficult for future cockroaches to get out.
Where do cockroaches lay egg capsules?
The place where cockroaches lay their eggs should be protected, dark and preferably with access to water and food. This will greatly increase the chances that all hatched larvae will survive. Again, the choice of location for the ooteca is largely determined by the attitude of the representatives of a particular species towards the offspring. If the Prussians choose hard-to-reach places in order to provide the eggs, and subsequently the larvae, with maximum protection, then black cockroaches can leave a capsule with eggs anywhere.
The laying of cockroach eggs in an apartment can most often be found:
- behind or under the baseboard;
- in cracks in the floor;
- under the sink;
- in the ventilation system;
- a place behind peeling wallpaper or peeling wall panels;
- the space behind the stove or behind the cabinets.
In most cases, oothecae are located either in the kitchen or in the bathroom, where water and food are easily accessible.
How often are egg capsules laid?
The frequency with which a female cockroach can lay eggs largely depends on its species. If we take the most common household pest, red cockroaches, as an example, then they make from 4 to 10 clutches during their life. The incubation period of Prussians, that is, the period from the moment the eggs appear to the moment the larvae appear, under normal conditions is from 2 to 5 weeks (if the temperature drops or there is a lack of food, the period may increase). Considering that the lifespan of a sexually mature individual is approximately 7–9 months, it can be calculated that, on average, a female German lays eggs once a month.
For comparison, in Madagascar cockroaches, the female carries an ootheca with eggs for 7 to 10 weeks, and lays eggs no more than 6 times during her life.
How many eggs does a cockroach lay?
The number of eggs that a female cockroach lays at one time also directly depends on the type of insect. If there are cockroaches in the house, then in one ooteca you can find from 20 to 50 cockroach eggs. This is one of the highest rates among cockroaches. Female American cockroaches can lay 14 – 16 eggs.
Female with ooteca
How many cockroaches hatch from one egg?
Many indicators vary depending on the species of cockroaches. For example, the size of representatives of the species affects how long it takes cockroaches to hatch from an egg. The larger the species, the longer the incubation period. The same pattern can be observed regarding the number of eggs that the female lays at one time. In smaller varieties, more larvae develop in the ooteca.
But as for the number of larvae in the egg, there are no discrepancies. Only one nymph always develops in one egg. Another thing is that many people make the mistake of calling an egg an ootheca. And one capsule can contain from one to several dozen baby cockroaches.
Kinds
Several main species can be found in apartments, which include small cockroaches. This is a black, red, and also a small brown cockroach. A characteristic feature of the latter is its localization in basements and sewer rooms.
In apartment buildings they rarely rise above the fifth floor, but they can cause a lot of trouble for the residents of the first ones. At the same time, small representatives of the cockroach family can coexist quite peacefully with colonies of larger red and black ones.
Features of the appearance of larvae
While in the ooteca, the embryos develop and grow. At a certain point, the larva becomes cramped in the egg, it gnaws through the wall and crawls out. For the first few days, hatched cockroaches remain in place and feed on the remains of the ootheca (if there is no more attractive food nearby). At first the nymph has a soft shell, but over time the chitinous cover gains strength.
After the first molt, the nymphs become more active, begin to settle in, and look for food.
With each subsequent molt (most often there are 6 of them), the larvae grow and acquire the features of adult insects. They develop wings, and later reproductive organs. After about 4-5 molts, the larvae look like adult cockroaches.
Endurance
Insects are able to survive in difficult conditions and are rightly considered the hardiest inhabitants of the planet:
- the Prussian goes without food and water for up to 30 days;
- black representatives of the species can survive without food for up to two months.
In the absence of food, individuals become aggressive. Adult cockroaches devour the young and weak, gnaw books and bite people.
It takes effort to kill pests. The chitinous shell reliably protects from impacts. The species is resistant to radiation, adapts to poisons and survives even without a head. An injured cockroach breathes through tiny tubes on its body and moves using reflexes. American scientists have found that an insect without a head lives 9-14 days. Death comes from hunger.
How long does it take for a cockroach to grow?
A newly hatched cockroach looks like a small white bug. The shell will not be white for long. As it hardens, it will darken and more and more resemble the color of an adult insect. But despite this, in the first few weeks it is not easy to recognize a cockroach in a small, fussy insect. The larva will resemble an adult in appearance only 3-4 weeks after birth.
The development of a red cockroach at the larval stage can take from several weeks to six months. These terms are quite arbitrary, since how quickly cockroaches grow is largely determined by external conditions, in particular the availability of water and food, the size of the colony, and the temperature in the room.
As for cockroaches of other species, a year or even more may pass from the moment the nymph appears until it reaches the adult stage. All this time, the size of the insects increases, but the adults no longer grow.
Ways to get rid of Prussians
There are several ways to help get rid of pet Prussians:
- Freezing. Cockroaches are heat-loving creatures, so in temperate climates they can only live in heated rooms. Thus, lowering the indoor temperature to minus 5 degrees is detrimental to insects of this species. This method helps to get rid of domestic cockroaches in dachas, but in an apartment or house with water heating it will not be possible to fight insects this way.
- Boric acid. This substance is sold in pharmacies and is inexpensive. Powdered acid is used for scattering in the habitats of Prussians or for preparing baits. To prepare the bait, the powder is mixed with egg yolk and powdered sugar.
- Ammonia. This method helps to get rid of Prussians if there are few insects in the house. Using the product is simple: you need to prepare a solution (a teaspoon per liter of water), rinse the floors and furniture with this solution.
- Traps. There are different types of traps - glue, electric or insecticidal. They all operate on the same principle: a bait is placed inside the trap, which emits an aroma that is attractive to cockroaches. If the trap is glue or electric, then the insects die when they fall into it. Insecticidal traps work differently: the insect eats the bait and receives a portion of poison. Then the poisoned individual enters places where insects accumulate and infects healthy fellow insects, carrying particles of poison on their legs and antennae.
- Gels. These products work in the same way as traps. Gels are packaged in syringes or tubes. Apply the product in droplets in the form of a dotted line on vertical and horizontal surfaces.
- Aerosols. This product helps get rid of cockroaches as quickly as possible. However, the effectiveness of aerosols is high only if the drug falls directly on the cockroaches.
So, the red cockroach is a small synanthropic (settles near a person) insect that can spread infections. Therefore, having noticed the Prussians appearing in the house, you need to immediately take measures to destroy them as quickly as possible, choosing the most suitable method of struggle.
How to destroy cockroach eggs?
It is almost impossible to get rid of cockroach eggs, this is explained by the fact that the ootheca protects them both from mechanical stress and from unfavorable environmental conditions. The capsule shell is dense and durable; toxic substances do not penetrate through it. In addition, the eggs inside the ootheca are protected by a layer of proteinaceous foam material. Therefore, they can withstand lower temperatures than adults and are protected from drying out.
Pest control
To destroy the entire colony of insects, the following steps must be taken:
- carry out disinsection treatment of the premises to destroy larvae and adult cockroaches;
- after 12–15 days, repeat the procedure to get rid of the larvae that hatched during this time.
When processing, you need to pay special attention to hard-to-reach places: crevices, cracks, the space behind baseboards, under the bathtub, joints with sinks and pipes.
Are there viviparous cockroaches?
Absolutely all representatives of cockroaches produce offspring by laying eggs. It is quite common to believe that some species, such as Madagascar cockroaches, reproduce by viviparity. If you observe the process of the birth of larvae, you may really get the impression that the female is giving birth to cubs.
Actually this is not true. The fact is that in certain species of cockroaches (including Madagascar ones), the ootheca with eggs is located inside the female’s body. Moreover, she remains there until the little nymphs appear. It turns out that, in fact, the cubs are born in the mother’s abdomen, but despite this, from a biological point of view, the process cannot be attributed to viviparity, since hatching from eggs takes place.
Interesting Facts
Finally, some interesting facts about the reproduction of cockroaches:
The duration of the gestation period for eggs can vary and reach 60 - 90 days (sometimes “pregnancy” stretches for six months). It is influenced by the female’s living conditions: the more favorable they are, the faster development will take place. Males of some species of cockroaches can organize real “fights” for the female they like: “butt” each other, make frightening loud sounds
And some even try to fly to attract the attention of a potential partner. American cockroaches and some other species do not require partners to reproduce. Fertilization of the egg occurs asexually without the participation of a male, and this is called parthenogenesis. Some types of cockroaches show care towards newborn larvae and protect them for some time
This is a kind of maternal instinct, which is rare among insects. Cockroaches are nocturnal; during the daytime they practically do not leave their shelters. And reproduction, accordingly, also takes place in dark places; the presence of light can interfere. Males and females can be distinguished by their appearance. Thus, male representatives are smaller in size, but their wings are more developed. And between the cerci at the end of the abdomen there is a genital plate (styles), with the help of which fertilization is carried out. The ootheca is a kind of guarantee of procreation, because it allows you to maintain a certain temperature of the eggs, as well as protect them from exposure to moisture and toxic substances. Domestic red cockroaches reproduce more quickly than, for example, American ones. And this is due to some differences in the life cycle: in red insects, puberty occurs earlier.
Now you know everything about how domestic cockroaches and other cockroaches reproduce.
