Of the 4000 plus species of cockroach, the most popular is the Madagascar “Hissing” Cockroach, Gromphadorhina portentosa. The Hissing Cockroach is one of the largest species of cockroach reaching a size of about 4 inches. The Hissing sound is made by actively forcing air out of the spiracles. In nature, the sound can startle a potential predator and allow a Hissing Cockroach opportunity to escape.
Hissing cockroaches are slow moving, lack wings and breed only slowly. The females lay an egg case (ootheca) like most cockroach species. Once the case is laid, the female will take the egg case back into her reproductive system to incubate the egg case. The larvae hatch inside the female and are born live. This is sometimes a shock to people who have a single female and suddenly find a large litter.
In the US, they do not thrive in the absence of human care. It is some concern that they could survive in Florida where permits are required to maintain breeding populations. However, the species lacks many of the traits necessary to be invasive.
For many reasons, the Hissing Cockroach is a popular insect zoo animal. They are large enough to be picked up and held without harming them, but slow enough that they are not a threat to escape. These qualities make them good animals for “insect petting zoos”. People who are otherwise afraid of insects can learn that insects are not slimy and do not necessarily bite or sting.
At Purdue, we use the Hissing Cockroaches in classes and outreach programs. Students can learn a lot about insects (and science) by making daily observations of a Hissing Cockroach Pet. Observations are the basis for developing scientific questions (hypotheses). Hissing Cockroach pets are useful for teaching students about the scientific method.