Cockroach The fecal pellets of cockroach become airborne after being dried and fragmented.   Cockroaches are one of the major sources of year-round allergens. They also carry infectious diseases and food poisoning bacteria. For people with poor living environments with serious cockroach infestation, cockroach allergy has been found to be a major factor in those attending hospital emergency departments with severe asthma.   Cockroaches are usually found around food storage areas or dustbins, kitchen sinks or draining boards, underneath or in cracks around cabinets (especially in the upper corners), behind drawers, around pipes or conduits, behind windows or door frames, behind loose skirting boards, on the underside of tables or chairs, and in the bathroom.   The source of cockroach allergens is less well defined. Possible sources include:   The digestive enzymes present in their fecal particles may play an important role. When the fecal particles of cockroaches get dried and fragmented, they become air-borne and inhaled.   Dust particles may become coated with the allergens of cockroaches and then enter the body when inhaled.   Some research suggested that the cockroach sexual pheromone-binding proteins may be the source of cockroach allergens.   Some studies found that the cockroach allergens have long lasting effects in infested places, even a few years after the cockroaches have been eradicated. These allergens can be effectively removed by repeated thorough cleaning with common cleaning agents.   Ways to reduce exposure to cockroach allergens German cockroaches can survive for 42 days on just water alone but only 12 days if the water supply is withdrawn, even if there is plenty of food to eat. Therefore reducing the sources of dampness at home leads to a reduction in the number of cockroaches. Reduce sources of dampness in the home (e.g. wipe draining boards completely dry after washing up the dishes and basin surrounds after cleaning your teeth), and maintain good air ventilation. Promptly dispose of all waste food and other waste matter in sealed bags or containers and keep the surrounding area clean. Keep food in sealed containers or inside the refrigerator. Don’t leave plates and other cookery unwashed overnight to become cockroach feeding sites. Keep pet food in re-sealable containers and do not leave food and water out all the time. Remove food crumbs regularly with an efficient vacuum cleaner. Seal entry sources into your home, such as those around pipework – an adult cockroach can squeeze through an opening only 1.6mm (1/16 inch) wide. Keep rooms uncluttered. This provides the cockroach with fewer hiding places. Seal cracks and crevices in woodwork. Do not overwater the houseplants that make excess moisture available to cockroaches. Inspect grocery bags for cockroaches before putting away in cabinets.   Species of cockroaches There are about 50 species of cockroaches, varying in size from 2 - 5 cm (3/4 - 2 inches). Some species live mainly outdoors, entering into your home only to breed or to search for food. The most common species found at home is the German cockroach which is about 2 cm long. Just a single pair of them can produce up to 30,000 offspring in one year.