The Little Giant: A Story of the Madagascar Hissing Cockroach
| Polish version is here |
The following article was originally published in the journal for educators Biologia w Szkole (eng. Biology in School) (1/2017):
Education can be understood as a concept tied to mental development and the expansion of human knowledge. The term comes from the Latin word "educatio," which means "raising." It can describe the knowledge level of an individual or that of broader groups, such as societies or entire nations. However, the meaning of education goes beyond that. It also encompasses the process of acquiring information, developing certain traits and skills, and strengthening them through practice.
In every discipline, instruction must take an appropriate form. This is particularly important in the natural sciences, where the phenomena under investigation should be precisely described and modeled. Testing proposed hypotheses through experimentation is essential.
Biology, as a branch of the natural sciences, should emphasize both the transmission of theoretical knowledge and its verification through observation and practical activities.
Unfortunately, in practice, biology lessons in schools are often taught in a largely theoretical way. Even though more advanced teaching tools are now being used, including multimedia presentations and rich collections of photos and videos, they cannot replace direct contact with living organisms and real natural processes.
Introducing live animals into the life science classroom offers unique educational opportunities. It enables learners to conduct fascinating observations, and when involved in the care of the organisms, it fosters empathy and awareness of living beings.
Educators and school administrators often express concerns about the potential cost of using living animals in teaching. While this concern is not entirely unfounded, I believe it can be addressed through creative and practical solutions.
By selecting suitable organisms, maintenance costs can be kept low. Caring for them should be simple enough to be managed by students under proper supervision. The organisms should also be resilient to changes in environmental conditions and pose no safety risks. Size is another key factor: animals that are too large may be impractical in a school setting, while those that are too small may require expensive equipment like microscopes. All these requirements are well met by the water flea Daphnia pulex, a small crustacean from the suborder Cladocera. I described how to keep this species in an earlier issue of Biology in School [1].
In this article, I would like to present another fascinating organism well suited for use in biological education: the Madagascar hissing cockroach.
Cockroaches
Roaches Blattodea are an order of insects that undergo partial metamorphosis (incomplete metamorphosis, hemimetaboly). In other words, their immature stages resemble the adults [2].
Their bodies are typically dark, often in various shades of brown. The head is almost entirely hidden under a large pronotum [3]. Most species have two pairs of wings: the first is tough and pigmented, while the second is membranous and usually folded underneath. Some species are wingless. Antennae are long, segmented, and covered in bristles. Their legs are adapted for rapid movement, and the abdomen ends in a pair of segmented appendages called cerci.
These insects thrive in warm environments; most species are native to tropical regions. Sixteen species have been recorded in Poland, of which only seven occur naturally (e.g., the dusky cockroach Ectobius lapponicus and the forest cockroach Ectobius sylvestris). The remaining species are synanthropic, having been introduced. Notable examples include the oriental cockroach Blatta orientalis and the German cockroach Blattella germanica, which are known carriers of disease.
How to Start a Colony?
Most species are relatively undemanding, so keeping them is not particularly difficult.
The ideal way to start a colony is with a moderately large number of individuals. Provide them with appropriate living conditions. An aquarium or insectarium works well, but even a clear plastic container can be used effectively.
The bottom of the container can be covered with a thin layer of peat mixed with sand or soil. Madagascar roaches do not burrow, so the substrate does not need to be deep. Add pieces of bark, cleaned roots, stones, cardboard tubes, or egg cartons to provide shelter, as these insects tend to hide. There should be enough hiding places as well as space for food and a simple water source, such as a moist sponge placed on a saucer.
As omnivores, these creatures accept both plant- and animal-based foods, such as fruits, vegetables, grains, or dry pet food. It's important to remove uneaten food before it molds and replace it regularly.
Regardless of the container type, it must be tightly sealed. Both nymphs and adults can climb smooth surfaces such as glass or plastic. The lid should be well-ventilated, with numerous small holes.
Occasionally spray the interior to maintain proper humidity. Keep the temperature above 20°C (68°F). Avoid strong lighting, as these insects are most active at night, though some movement can be seen in dim light during the day.
A larger container can be used for a small group (Photo.1).
Observations
The Madagascar hissing cockroach Gromphadorhina portentosa, a member of the Blaberidae family, inhabits the forest undergrowth of Madagascar. This species is captivating for many reasons, which will be explored in this article. It is not protected and is not listed under CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora) [4]. As a tropical species, it cannot survive or reproduce in Poland’s temperate climate. In controlled conditions, it poses no threat to human health and is frequently bred as a food source for reptiles such as lizards and snakes.
These insects can grow quite large, up to 8 cm (3.15 in). Their coloration varies; the most common form has a dark brown head and thorax, and a slightly lighter brown abdomen (Photo.2).
Their size makes them ideal for studying external anatomical features. The underside is easiest to examine, although roaches can quickly flip back over when placed on their backs. One way to slow them is to chill the container in a refrigerator for about 15 minutes. Lower temperatures reduce activity, but the insects recover once warmed. Take care not to chill them excessively.
A safer method is to place the insect on its back and cover it with a Petri dish. The animal instinctively pushes against the glass, making observation easier (Photo.3).
Like other insects, its body is divided into head (caput), thorax, and abdomen (urosoma) and is flattened from top to bottom. The exoskeleton is tough yet flexible, made of chitin, a polymer of N-acetylglucosamine produced by the hypodermis. It protects, shapes, and serves as an attachment point for muscles.
The head develops during embryonic stages through the fusion of five segments. The compound eyes are small, reflecting nocturnal habits. Sensory input mainly comes from long, mobile antennae, which are modified appendages, as are parts of the chewing mouthparts. Insects can have different head orientations such as prognathous, orthognathous, or hypognathous [5].
The hissing cockroach’s head is hypognathous and concealed under the broad pronotum (Photo.4).
The thorax has three segments, each bearing one pair of legs. While this species is wingless, in other roaches, wings are attached to the second and third thoracic segments.
The legs are muscular and efficient for movement (Photo.5). The coxa connects the leg to the thorax, followed by the trochanter, femur, and tibia, which is spiny. The leg ends with a five-parted tarsus.
Under magnification, the tarsus reveals three important structures: two claws (unguis) and the adhesive arolium between them (Photo.6). These enable grip on rough surfaces and adhesion to smooth ones. Additional pads called euplantulae serve a similar function [6].
The abdomen is covered with a thinner cuticle and connects broadly to the thorax (a sessile type). It contains internal organs and fat reserves. The cerci at the end serve various sensory functions.
This species shows sexual dimorphism. Males have horn-like structures on the pronotum (Photo.7), while females have smoother, more rounded features.
When these features are ambiguous, sex can be more reliably determined by examining the terminal abdominal sternites (Photo.8).
Reproduction in these insects is influenced by humidity changes. Males compete for mates. As ovoviviparous animals, they produce oothecae with several dozen eggs. Nymphs receive a secretion from the female and stay under her protection during early development, molting several times before maturing.
A remarkable feature of this species is sound production. Both sexes hiss to deter predators, during mating, or when startled. A recording is available in the supplementary materials.
Unlike insects that produce sound via stridulation, these cockroaches use their respiratory system. Air is expelled through specialized spiracles by contracting muscles around them [8].
All observations described here are non-invasive and repeatable. Lifespan varies with temperature; nymphs live 6–8 months, adults up to 2–3 years. Remove any dead individuals promptly.
Although many people initially react with fear or disgust, this often results from unfamiliarity. In my experience, curiosity quickly replaces apprehension, and students soon ask to hold the insect, which often marks the beginning of deeper engagement (Photo 9).
Summary
Madagascar hissing cockroaches can play a valuable role in biology instruction. They are excellent for demonstrating insect anatomy, morphology, and ecological adaptation. Just as importantly, they help foster emotional connections between students and the natural world, which is as vital as the transfer of knowledge itself.
References:
- [1] Ples M., Oko w oko z rozwielitką (eng. Face to face with a Daphnia), Biologia w Szkole (eng. Biology in School), 5 (2015), Forum Media Polska Sp. z o.o., pp. 53-56 back
- [2] Hempel-Zawitkowska J., Zoologia dla uczelni rolniczych, Wydawnictwo Naukowe PWN, Warszawa, 2007, pp. 226 back
- [3] Zahradnik J., Przewodnik: Owady, Wydawnictwo Multico, Warszawa, 2000 back
- [4] CITES browser, online: http://checklist.cites.org/#/en, [dostęp: 05.12.2016] back
- [5] Razowski J., Słownik entomologiczny, Państwowe Wydawnictwo Naukowe, Warszawa, 1987 back
- [6] Bazyluk W., Klucze do oznaczania owadów Polski, Karaczany – Blattodea, Modliszki – Mantodea, Państwowe Wydawnictwo Naukowe, Warszawa, 1956 back
- [7] Głuch W. (red.), Biologia: Słownik encyklopedyczny, Wydawnictwo Europa, Warszawa, 2001 back
- [8] Nelsen M. C., Sound production in the cockroach, Gromphadorhina portentosa: The sound-producing apparatus, Journal of Comparative Physiology, (1) 1979, pp. 27-38 back
All photographs and illustrations were created by the author.
Addendum
Below is a recording of the sounds made by a Madagascar hissing cockroach when disturbed by the opening of the insectarium lid:
Marek Ples