Cockroaches are a common household pest in New Zealand. While they are only a low-level health risk, cockroaches thrive in unhealthy environments and they can transmit a number of diseases.
All cockroaches are pests. The biggest cockroach pests in New Zealand are the American cockroach (Periplaneta americana) and the German cockroach (Blattella germanica).
View images of different cockroach types - Landcare Research website
Where cockroaches live
Cockroaches prefer damp, dark places. They are often found inside walls, behind household appliances and in cupboards.
Cockroaches thrive in warm and damp conditions and will dehydrate if the environment is too dry. However, they can survive in extreme conditions for short periods of time. Cockroaches can survive months without food and up to 4 weeks without water. This makes them very difficult to get rid of.
Health risks from cockroaches
Cockroaches can transmit diseases like dysentery, salmonella and diarrhoea. Their eating habits also expose humans to dangerous diseases. Cockroaches can eat a range of foods, from faecal matter to fresh food intended for people to eat. If cockroaches contaminate your food or the surfaces you use, you could get sick.
Preventing cockroach infestations
You can reduce your chances of a cockroach infestation by:
- filling cracks in walls and foundations
- keeping living areas dry and clean
- disposing of rubbish
- removing human waste and food waste from the home quickly and efficiently.
If you already have cockroaches, you might need to set baited traps or apply an insecticide to the area. Insecticides work best when applied to areas where cockroaches hide during the day or where they pass through at night time.
It is vital to keep your home clean and dry to stop you from getting cockroaches in the first place.
Read about preventing pest infestations - Tenancy Services website
Cockroach lifecycle
Cockroaches undergo 3 stages of development: egg, nymph and adult.
The egg hatches into a nymph, which looks similar to the adult cockroach. The nymph then undergoes a series of moults before developing into a fully reproductive adult cockroach. The length of this process varies, and may take anywhere between a few weeks to a year to complete the cycle.
Female cockroaches are able to lay hundreds of eggs in their lifetime.