American cockroach (Periplaneta americana)

The American cockroach is sometimes called the ship cockroach, Bombay canary, waterbug (US).

The American cockroach is an invasive cockroach.

Found worldwide, common in many tropical and sub-tropical areas. In more temperate areas they will inhabit indoor areas and sewers, especially in the cooler seasons. American cockroaches tend to be more common on the warmer past of the North Island of New Zealand.

American cockroaches prefer warm to hot, moist habitats, although they will live in dryer areas (eg. Roof voids) as long as they have access to water. Typically they are an outdoor cockroach, living in the leaf litter.

They are considered peridomestic cockroaches in that they live in and around buildings – garden beds, sewers, garbage bins, sub-floors and roof voids and common locations, moving inside buildings when looking for food. However, they will happily set up in kitchens and bathrooms given the opportunity.

American cockroaches live in aggregations – cockroaches of all ages (young nymphs to adults). Whereas the cockroaches don’t activity co-operate as a community, the young cockroach nymphs, which tend not to leave the harbourage, benefit from this arrangement as they feed on the droppings and vomit of older cockroaches.

American cockroach adults:

Colour: Mid brown / red, with a pale band around the pronotum (shield covering the head)

Size: Up to 40 mm

Males: Wings longer than body

Females: Wings shorter than body

American cockroach nymphs:

Colour: Young nymphs are dark brown / black with older nymphs reddish brown, with darker edges on the posterior edge of body segments

Size: From 6-30 mm

American cockroach life-cycle:

Eggs: 16 eggs per ootheca (egg case). Ootheca deposited near food source a couple of days before egg hatch.

Number of nymphal stages/moults to adult: Between 6 and 14

Length of life-cycle (Egg to adult): 600 days

Life span of adult: 12 months+

American cockroaches will eat everything! They are scavengers that will eat any organic matter – they will even eat their dead nest mates!

• The adults are capable of short flights, but only in warmer weather
• Sometimes confused with the Australian cockroach, which has pale band along the outer edge of the wing covers
• The droppings from American cockroaches – small, dark pellets – can be confused with mouse droppings to the untrained eye
• A heavy cockroach infestation generates an unpleasant, musty smell.

Cockroaches are viewed as “dirty” insects, mainly due to their association with sewers and human waste. Indeed, they have been shown to carry a wide range of different diseases, in particular gastro bacteria such as Salmonella and E. coli, as well as a number of parasitic worms. When they move across food preparation surfaces and feed on any exposed food, there is always the potential to transfer these diseases to humans.

The spent skins and droppings of the American cockroach contain allergens that can trigger allergic reactions and asthma attacks, although allergic reactions are more common to German cockroach infestations which are more common indoors.

Good hygiene is key to preventing a cockroach infestation:

• Keep food preparation areas clean – clean up food spills and clear away dishes after meals
• Make sure the dishwasher is run regularly
• Regularly clean cooker, grill, extraction fan, dishwasher and refrigerator (especially underneath)
• Don’t leave unfinished pet food out overnight
• Fix any leaks and areas of moisture
• Fill any cracks and crevices, that would allow cockroaches easy access from the outside
• Ensure rubbish is put into sealed containers