NC State Extension Publications

Description and Biology

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The Australian cockroach, also known as a waterbug or the “shad roach,” Periplaneta australasiae, is an inch long, dark brown cockroach with pale yellow to orange bands on the outer margins of the forewings and an irregular pale band around the prothorax that defines a two-lobed dark spot. Eggs are laid in a brown, oval ootheca or egg capsule about 3/8 inch long that is carried by the female for a few days and then glued to some substrate usually in a crack or crevice. Females produce 20 to 30 egg capsules in their live spans of 4 to 6 months. Usually 12 to 24 nymphs hatch between 40 days and 3 months. It takes about a year for this species to develop into the adult stage. Young nymphs are small and very dark brown. They have a pale band across the thorax and two pale spots on the abdomen. Older nymphs are variously spotted and develop wing buds as they molt and grow. The Australian cockroach prefers warm, damp places outdoors or in greenhouses, interiorscapes, and other buildings that have warm, damp situations. When a pest in buildings, it usually infests only the bottom floor.

Australian cockroaches resemble American cockroaches

Australian cockroaches resemble American cockroaches except for the light markings on the thorax and wing margins.

 distinguish Australian cockroaches

Here is a closeup of the markings that distinguish Australian cockroaches.

Australian cockroach ootheca

Australian cockroach oothecae are usually placed in cracks or crevices.

Host Plants

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Australian cockroaches sometimes feed on tender seedlings and tender foliage of ornamental plants, although they also feed on starchy substances including unprotected food.

Residential Recommendations

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Fortunately, the Australian cockroach is not particularly resistant to pesticides. However, some pesticides cannot be used in interiorscapes and hobby greenhouses. Consider using abamectin cockroach baits. These baits are highly effective for other pest species of cockroaches, and there is no reason to believe they will not give more than adequate control of the Australian cockroach.


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This Factsheet has not been peer reviewed.


Professor Emeritus
Entomology and Plant Pathology

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Publication date: March 15, 2017
Revised: Dec. 22, 2021

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