Creepy Crawly Hissing Roaches
A family of cockroaches lives in a small aquarium in my laboratory. They are not your everyday
cockroaches that are sometimes found in people’s kitchens. These are giants, at least as far as
cockroaches go. They are Madagascar Hissing Cockroaches (Gromphadorhina portentosa) and can grow
to be two or more inches long. Don’t worry, they are tropical natives and could not survive long
outdoors in Ohio climates. They are harmless to humans, do not bite, and are not know to carry any
human diseases. However, just to be safe, their aquarium is covered and the top of the glass walls has a
coating of petroleum jelly which keeps them from climbing out.
These cockroaches are from the large island of Madagascar in the Indian Ocean off the east coast of
Africa. The island is famous for its wide variety of unusual wildlife, including several species of lemurs
found nowhere else in the world. Madagascar has tropical rainforests and it is in these forests that the
hissing cockroaches live, usually in leaf litter or in a fallen and decomposing log.
Hissing cockroaches lack wings but they make up for their inability to fly by being excellent
climbers. They can climb up glass panes and have no trouble climbing into the tall trees of the
rainforest. They are herbivores and detritivores, eating green leafy material, ripe fruits, dead leaves,
and soft plant parts.
The roaches really do hiss. They do this by squeezing together the top and bottom shells of their
abdomen. This squeezes the air out of holes called spiracles along the side of their body and the
escaping air creates the hissing sound. The sound is only produced by the spiracles on the fourth
abdominal segment that have special modifications to make the sound. There are at least three
different types of sounds that are produced. The most common, the disturbance hiss, is what I hear
when I pick up one of the critters. It probably serves to scare predators. A second sound is the female
attraction hiss and the third is the aggressive hiss. The latter two sounds are made only by male hissing
cockroaches.
Some people keep the hissing cockroaches as pets. The cockroaches eat little and their habitat takes up
relatively little space. In nature they are detritivores, but in captivity they can eat leafy greens and high
protein pellets such as dried cat food. Unlike some other species of roaches, this species does not live in
houses, except as pets, and is not considered a pest. However, seeing one run across your floor might be
a little alarming.
Hissing cockroach females retain their eggs inside their body until the eggs hatch. They may hold as
many as 60 eggs in their abdomen. After the eggs hatch into nymphs, the nymphs leave their mothers
body looking very much like small versions of the adult except they are much smaller and nearly
white. Within a few days, the skin (exoskeleton) of the nymphs will darken into shades of brown and
even black.
Believe it or not, islanders in Madagascar will sometimes cook and eat these large roaches. The insects
do contain quality protein and fat and are nutritious. However, before they are cooked they contain a
mild neurotoxin that may serve to deter predators. I think I will pass on this culinary opportunity,
cooked or raw.
Photo: A Madagascar hissing cockroach climbing the glass wall of its aquarium home at the University of
Mount Union.
Photo by C. McClaugherty