Further you will learn:
- how many cockroaches hatch from one egg;
- how the cockroach eggs and egg capsules look (so-called ootheki) and how many eggs are contained in one such capsule;
- how and where the egg laying process takes place and the subsequent appearance of young cockroaches;
... and other interesting facts concerning the "birth" of cockroaches from eggs.
Probably, someone will seem strange, but only one tiny larva hatch from one egg of cockroaches, which later, after several lines, turns into an adult insect. This is important: in one egg there is only one cockroach.
It is not difficult to explain this: more larvae can not fit here, and the egg itself is a developing egg, which can only turn into one embryo.
In the photo - cockroach eggs:
On a note
Theoretically, two twin larvae can develop from one cockroach egg, as in other animals. However, such cases are very rare, and, in general, one cockroach almost always develops from one egg.
It is important not to confuse the egg and a special egg capsule, or ootheca, in which a lot of such eggs are placed. By the way, it is because of the compact swelling that the "pregnant" female of the red cockroach carries with itself, many people believe that in one egg of cockroaches there are many future pests - they confuse capsules with eggs.
Let's touch this point in more detail and see how many cockroach eggs are in the ootheke and how such a capsule is arranged.
Eggs of cockroaches and egg capsules (ootheki)
Eggs of cockroaches of almost all species in the body of the female are "packaged" in a special shell, which rapidly solidifies in the air and forms a characteristic capsule.
Such a capsule is called ooteca (from the Greek "oo" - an egg, "tekos" is a repository) and serves to protect vulnerable eggs from the effects of unfavorable environmental factors. It provides a high survival rate of cockroaches in nature as well as in human habitation.
On a note
Ooteca is also found in other species of invertebrates: in addition to cockroaches, for example, it is characteristic of mantises and mollusks.
The oocae of cockroaches can have different shapes, sizes and colors, depending on the type of insect. For example:
- The black cockroach oocyte has a dark brown color, a length of about 12 mm, a width of about 6 mm and a well-marked crest on the surface;
- the ospot of the Prusaka is red, about 8 mm in length, with well-marked transverse constrictions;
- The Madagascar cockroach has a long ootheka, it has a light yellow color, the dimensions are of the order of 25x4 mm.
The photo below shows the appearance of the ointech of the cockroach:
And in the next picture you can clearly see how the ootheke of the Madagascar sizzling cockroach looks:
Despite the relatively high strength and hardness of the wall, the ootheque allows the developing embryos to breathe, resembling a bird's egg shell.
The number of eggs in each ootheke is determined by the appearance of the cockroach. So, for example, in red cockroaches in each capsule there are on the average 20-30 eggs, rarely - up to 50. They lie very tightly to each other in 4 even rows - two in height and two in width.
The eggs themselves have a tiny size - about 1 mm in length and a few tenths of a millimeter in width. They are light yellow or white, translucent, and through their shell you can even see with a magnifying glass an embryo.
The photo below shows how the eggs of cockroaches look inside the ootheca:
An ootheque is formed during the period of the laying of eggs by the cockroach. In a special chamber in the abdomen of the female a large amount of sticky secretion is excreted, into which eggs, coming from a special organ, are literally dipped.
When the process of forming eggs ends, the secret is released for a while, closing the ootheka from the inside. By this point in most species of cockroaches the capsule for a considerable part of its length leaves the body of the "pregnant" female and remains attached to the end of the abdomen for some time.
In this capsule, cockroach eggs develop from 30 to 75 days. The fastest development is in conditions of high temperature (above 30 ° C) and humidity, but when the temperature drops below 15 ° C, their development stops, recommencing with the return of heat. This allows the population to survive the cold.
It is interesting
The adult cockroach dies at temperatures below -5 ° C and above + 45 ° C, while its ootheque normally transfers short-term cooling to -10 ° C and overheats to + 55 ° C. In addition, insecticides are poorly affected by ointec (and many of them have virtually no effect). For example, in the Prusak, whose females carry a capsule at the end of the abdomen until the end of the development of the larvae, if the mother dies from the effects of the insecticide, the eggs in the ootheque continue to develop, and later the young nymphs still hatch from them.
Different species have different care for eggs and their protective capsule.
For example, females of black cockroaches lay off edemas, and, thus, leave their eggs to the mercy of fate in 3-4 days after the ootheca completely forms. Next two more months the capsule develops without any protection. If such ooteka at this time will find predators or parasites, then they will destroy the eggs. In many respects, that is why red cockroaches everywhere oust blacks - they just eat their eggs.
The same prusak, as well as various exotic species, for example, ash and Madagascar cockroaches, show a certain concern for the offspring. Female red cockroaches are ooteca at the end of the abdomen until hatching of the larvae, and from danger they can at least carry it away.
And in the same Madagascar ooteca develops in the body cavity, and only a few times a day the "pregnant" cockroach exposes it to the outside for airing. Larvae hatch also inside the mother's body, but practically at the same time they leave the brood chamber. The observer of this process creates a feeling that the cockroach gives birth (that it is supposedly viviparous), although in fact, all cockroaches, without exception, lay eggs, it is just that in some species eggs develop to the larval stage inside the mother's abdomen.
The photos below show how the female of the Madagascar sizzling cockroach gives birth:
Depending on the type of cockroach, the number of "pregnancies" and females that are hatched by the female for life is also different. Thus, a female Prusaka can produce up to 9 capsules (of which "more than 250 larvae" are born), although usually the "average" female produces about 3-4 ootecs for life.
In this case, the female of the Prusaka is clearly visible, and in large tropical species, in which the capsule is hidden in the body, it may not be clear that the female is in an interesting position.
How does the process of hatching cockroaches from eggs
Embryos of cockroaches constantly move inside the egg, absorbing embryonic fluid and nutrients. When they reach such a size that they no longer fit in the egg, then rupture its shell and begin to gnaw the ridge of the ointech.
In those species, the females of which lay the capsule, after the exit of the larvae from the ootheka remains a strong outer shell. In those whose oothek develops within the body of the female, its membrane is very soft, and by the time of the appearance of the larva it completely bursts, and the offspring leaves the mother's body in a free state, after which the female gets rid of the remains of the capsule.
In the video at the end of the article you can see how "cockroaches" are born.
Large species can breed up to 60 young larvae at one time, but in general the normal number of young individuals is 25-35. The same number of young cockroaches hatch from the ointec of ordinary domestic species.
Next on the photo you can see what the black cockroach looks like and the newborn larvae around it:
As a rule, the whole process of "birth" of cockroaches lasts from several minutes to several hours. After the birth, the larvae are usually very light, almost white, but then darken as the chitin cover hardens.
Are there viviparous cockroaches?
Cockroaches are not viviparous creatures. The terms "egg-living" and "egg-laying" apply to these insects.
If the embryo develops in the egg and does not receive nutrition from the mother's organism in the process of development, but is in the body of the female, then this method of reproduction is called egg-planting.
Those cockroaches whose females simply leave their ooteca to the mercy of fate are typical oviparous insects. The same species, in which the eggs develop inside the female body, and the nymphs hatch at the same time as the exit from the brood chamber - egg-living.
Therefore, the terms "pregnant cockroach" and "viviparous cockroaches" are not completely correct - only viviparous animals are truly pregnant.
From the scientific point of view, the expression "cockroaches give birth" is not entirely correct. This process is called not birth, but hatching.
In the photo - female Madagascar cockroach with nymphs appearing from her abdomen:
Features of the appearance of larvae
Most of the cockroaches do not show any concern for the offspring. Even with the famous red cockroaches after the exit of the larvae from the ootheka, they just stay near it for some time, and, therefore, near the female, but within an hour or two they scatter and hide in convenient shelters.
Taking into account the fact that the female tries to lay aside the ootheka in a place hidden away from the main shelter of other adult insects, for the first few days the larvae have little contact with other individuals.
In some tropical species, females take care of only larvae that have just appeared. In the same Madagascar cockroaches, babies gather under the belly of the mother, who for several hours continues to guard them, hisses at the approach of the enemy and can even make frightening attacks. However, by the end of the first day after hatching, the young cockroaches are spreading, and the mother's cares for this end.
On a note
Special care for babies is shown only by relic cockroaches. They live in small colonies with a rudimentary hierarchy, and their offspring are courted as carefully as in termite nests.
Given the fact that nymphs of cockroaches immediately after hatching can eat, they do not need long-term care, and they quickly become ordinary equal members of the family.
Interestingly, the larvae of cockroaches immediately after the birth of often trying to eat their own ootec. They need it as a source of protein in the first hours of life.
Where are the cockroaches laying capsules with eggs?
Female cockroaches try to lay the capsule with eggs in the most secluded and safe places. In nature, these are spaces under stones, fallen trees, deep under a layer of rotted leaves, and in some species - even in the ground or in dry wood.
Similarly, in the apartment - cockroaches and then lay eggs in the most secure places, for example:
- In the crevices between the walls of the furniture;
- under the bedside tables;
- between the sink and the bedside table below it;
- behind skirting boards;
- in the ventilation ducts;
- under the bathroom;
- on the shelves in the pantry.
Sometimes when cleaning the apartment owners can come across the dry shells of the ootek prusakov - they are already empty, and they simply throw out in the trash. But if a large black cockroach is found, it is useful to destroy it, because with a high probability several dozens of future pests can hatch from it.
Do not expect that if you make a raid in search of "eggs" cockroaches and destroy several capsules, then this will bring the cockroaches out of the apartment completely. Those capsules that can be found are more likely to be empty, but the number of undetected ones will be much larger (red cockroaches carry them with them).
Yes, and the search for ootecs, even in the case of fighting black cockroaches - a very time-consuming and inefficient exercise. It is much more reliable to remove pests by simply conducting a disinfestation in the room.