Australian Cockroach

The Australian cockroach, <em>Periplaneta australasiae</em> (Blattodea: Blattidae), is a large peridomestic species measuring 27–35 mm as an adult, closely resembling the American cockroach but distinguished by a pronounced pale-yellow margin around the pronotum and yellow streaks along the lateral base of each forewing. Both sexes are fully winged and capable of gliding flight in warm conditions. Under optimal conditions (29°C, 65–80% RH) the lifecycle spans roughly 6–12 months, with females producing 20–30 oothecae over their lifetime, each containing 22–24 eggs that hatch after 30–40 days. Nymphs pass through 9–12 instars over about 6–12 months before reaching adulthood, with adults living an additional 4–8 months.

Primarily nocturnal and strongly thermophilic, <em>P. australasiae</em> thrives in warm, humid subtropical and tropical climates and readily invades structures when outdoor temperatures drop or moisture becomes limiting. It is a partial phytophage — more inclined than other <em>Periplaneta</em> species to feed on plant material, soft fruit, seedlings, and greenhouse crops — but is also fully omnivorous, consuming starches, decaying organic matter, and food residues. Adults are attracted to lights at night and disperse readily by flight, which facilitates rapid indoor invasion. Populations mechanically transmit bacteria (including <em>Salmonella</em> and <em>E. coli</em>) and fungal spores, and their shed cuticles and frass are recognized indoor allergens implicated in asthma.