Gromphadorhina portentosa

About Gromphadorhina portentosa

The Madagascar hissing cockroach is one of the largest cockroach species kept in captivity. Native to the forests of Madagascar, these wingless, heavily-built insects are famous for the loud hiss they produce by forcing air through modified breathing pores called spiracles — they have no vocal cords. Both sexes hiss when disturbed, but males also hiss during territorial disputes and courtship.

Males are easily distinguished by the large, prominent horn-like bumps (pronotal horns) on the pronotum behind the head. Females have a smoother, more rounded pronotum. As a tropical species, they cannot survive at room temperature in temperate homes without a heated enclosure — they pose no infestation risk.

Enclosure

A 40×30×30 cm plastic or glass enclosure suits a colony of 5–10 adults. They are strong climbers, so ensure the lid fits tightly or apply a thin band of petroleum jelly around the top rim to prevent escapes. Provide:

• Coco coir or organic topsoil substrate, 3–5 cm deep
• Egg carton flats or cork bark stacked vertically for hiding and climbing
• Good ventilation — mesh or drilled lids work well
• A shallow water dish with cotton wool or water crystals to prevent drowning

Mist one side of the enclosure every 1–2 days. They tolerate a range of humidity but thrive when it stays between 60–75%.

Feeding

Hissing cockroaches are generalist detritivores and will eat almost anything organic:

• Fresh fruit and vegetables: apple, carrot, banana, sweet potato, leafy greens
• Dry food: oats, fish flakes, dog or cat kibble for protein
• Leaf litter and decaying wood for fibre
• Calcium sources: cuttlebone or eggshell — important for breeding colonies

Remove uneaten fresh food within 48 hours to prevent mould.

Behaviour & handling

These are social insects and do best in groups. Males will spar by pushing each other with their pronotal horns — this is normal dominance behaviour and rarely causes injury. They undergo incomplete metamorphosis: nymphs hatch as miniature versions of the adults and moult several times before reaching full size over 6–8 months.

Hissing cockroaches tolerate gentle handling well. They grip firmly with their tarsal pads but do not bite or sting. Avoid grabbing or squeezing — let them walk onto your hand instead.