Cockroaches are ancient insects that have mostly stayed the same over the ages. There are 4600 species cataloged worldwide, with 30 interacting with humans regularly. These insects are known for being quite resilient and can survive extreme weather, ranging from the Arctic cold to the heat of the desert. While these insects are considered pests, only a handful are harmful to humans, and most aren’t offensive.
The longest cockroach is the Megaloblatta longipennis reaching over 3.8 inches, while certain Attaphila cockroaches are as small as 0.137 inches.
Weight: 0.0035-1.2 oz
The heaviest cockroach is Australia’s giant burrowing cockroach, which weighs up to 1.2 oz.
Body and Coloration: Cockroaches have not changed much over time, almost appearing to be primitive in body structure. Their bodies are flat and broad, their heads small, and they have mouthparts with mandibles and salivary glands.
A cockroach’s thorax has three segments, while its abdomen has ten. Its entire body is covered with a thick exoskeleton. The wings of all cockroach species are attached to the 2nd and 3rd thoracic segments, while each pair of the insect’s legs is attached to each part of the thorax.
The abdomen has ten segments, each with spiracles for respiration. The last segment also contains the reproductive organs of the species – an aedeagus in the males and spermatheca and an ovipositor for females.
Most cockroaches are a reddish brown color, though some show different coloration, like the seven-spotted cockroach, which is black with white spots.
Cockroach Image
Cockroach Photo
Distribution
Cockroaches have a worldwide distribution, with some species even living in the Arctic. Most species tend to prefer the tropics or the subtropics.
North America is home to around 50 cockroach species, while over 450 of these insects live in Australia.
Habitat
Due to their high adaptability, cockroaches can survive in various environments and habitats. While most live in dead plant material like bark cavities, leaf debris, and rotting wood, other species can be found in more specialized biomes. These include aquatic environments, arid regions, and the canopies of particular forests.
How long do they live
Cockroaches are long-lived insects and can survive for up to 20-30 weeks if they have adequate access to food and water.
What do they eat
They are omnivorous and not at all picky when it comes to food. An average cockroach feeds on bread, cloth, dead arthropods, fruit (ripe and rotten), glue, hair, leather, paper, skin flakes, and the starch in book bindings.
Behavior
These insects are social and form groups, with some species even displaying parental care toward their offspring.
This gregarious behavior is further displayed in decision-making, as younger or inexperienced cockroaches will often act similarly to the rest of the group. They will often form large groups near a suitable food source or a hiding place if enough individuals are aggregating there.
However, this doesn’t mean that a single cockroach does not display individuality. Studies show that if isolated a cockroach will show personality traits not displayed by other specimens. This indicates that decisions taken by a group are not the result of individual choices but collective choices.
Most cockroaches are nocturnal, with a few exceptions, like the Asian cockroach, which is attracted to bright surfaces and pale colors.
Cockroaches make a wide variety of sounds with the help of stridulatory organs and modified spiracles on the 4th abdominal segment. These noises include buzzing, chirping, hissing, whistling, and even rhythmic tapping.
Pictures of Cockroaches
Baby Cockroach
Predators
These insects are preyed upon by amphibians like frogs and toads, beetles, spiders, and small mammals like mice and shrews.
Adaptations
The exoskeleton of a cockroach is covered with wax, allowing it to repel water.
Their long hind legs allow them to jump easily over long distances, letting them quickly escape predators.
While lacking any specialized adaptations due to their primitive nature, they are incredibly hardy insects. They can survive most threats due to acquired immunities and toxin resistance.
How do they reproduce
The reproduction of the cockroach revolves around pheromones, with the male using a combination of them and several courtship rituals to attract a mate. The males also employ a series of aggressive hissing sounds. Copulation takes place while the insects are facing away from each other as their genitalia remains in contact. Parthenogenesis has been observed in specific cases.
Cockroach Eggs
Cockroach Nymph
Life Cycle
After mating, the female drops the fertilized eggs from her ovipositor. While a female can lay 300-400 eggs under favorable conditions, there have been records of even more eggs being laid by certain specimens. Laying an egg can take up to five hours, with the eggs displaying a white coloration. Once the hatchling begins to gasp for air from inside the egg, they begin to hatch thanks to the difference in pressure.
Initially, the nymphs are white before darkening after four or so hours. The nymphs generally resemble the adults, lacking only the genitalia and fully developed wings. It takes 3-4 months for the development from egg to adult.
While cockroaches are generally not considered by most people as worth conserving – about four species are considered pests – several of them are at risk of going extinct. Gerlach’s cockroach is classified as “Critically Endangered” or “CR” per the IUCN. In contrast, Lord Howe’s cockroach may be extinct on Lord Howe’s Island. The latter still resides in other parts of New South Wales but is still endangered.
The reason for this steep decline in wild cockroaches is a loss in habitat and the destruction of the species by humans, who consider them pests.
Cockroach – FAQs
1. Do cockroaches bite?
As their mouthparts aren’t strong enough to pierce most objects, cockroaches are rarely seen biting. They are most likely attempting to feed on dead skin flakes or food scraps.
2. Can a cockroach survive a nuclear apocalypse?
While cockroaches may resist certain forms of radiation, exposure to concentrated forms of radiation from a nuclear explosion would most likely kill them. The idea that cockroaches can withstand a nuclear bomb comes from rumors that the insects were seen scurrying about in the aftermath of Hiroshima and Nagasaki.
3. Do cockroaches carry diseases?
Cockroaches themselves do not cause any diseases. But they act as a vector for several disease-causing organisms like bacteria, fungi, mold, and viruses.
Interesting Facts
Cockroaches and humans have had an exciting history. A 2014 study indicates that we as a species have an evolutionary aversion to these insects. Despite this, cockroaches are used in research thanks to their resilience, consumed as food and medicine in countries like China, and some species, like the Madagascar hissing cockroach, are even reared as pets.
Russian scientists sent a cockroach named Nadezhda into space, where she became the first animal to conceive and produce offspring in space.
Dubia cockroaches are raised as food specifically for insectivorous pets.
