Among the best-known pest species are the American cockroach, Periplaneta americana, which is about 30 mm (1.2 in) long; the German cockroach, Blattella germanica, about 15 mm (0.59 in) long.
The Asian cockroach, Blattella asahinai, also about 15 mm (0.59 in) in length; and the Oriental cockroach, Blatta orientalis, about 25 mm (0.98 in).
Cockroaches are one of the most commonly noted household pest insects. They feed on human and pet food, and can leave an offensive odour. They can also passively transport microbes on their body surfaces including those that are potentially dangerous to humans, particularly in environments such as hospitals.
Cockroaches have been shown to be linked with allergic reactions in humans. One of the proteins that triggers allergic reactions has been identified as tropomyosin. These allergens have also been found to be linked with asthma.
General preventive measures against household pests include keeping all food stored away in sealed containers, using rubbish bins with tight lids, frequent cleaning in the kitchen, and regular vacuuming.
Any water leaks, such as dripping taps, should also be repaired. It is also helpful to seal off any entry points, such as holes around baseboards, between kitchen cabinets, pipes, doors, and windows with some steel wool or copper mesh and expanding foam or silicone caulk.
Diatomaceous earth applied as a fine powder works very well to eliminate cockroaches as long as it remains in place and dry. Diatomaceous earth is harmless to humans and feels like talcum powder. Most insects, including cockroaches, are vulnerable to it.
Some cockroaches have been known to live up to three months without food and a month without water. Frequently living outdoors, although preferring warm climates and considered "cold intolerant", they are resilient enough to survive occasional freezing temperatures. This makes them difficult to eradicate once they have infested an area.
