Cockroaches are the most common and troublesome pests in many homes. Common types of cockroaches in Hong Kong include Periplaneta americana (American cockroach), Periplaneta australiasiae (Australian cockroach) and Blattella germanica (German cockroach).

Biology and Characteristics of cockroaches

• Cockroaches pass through three stages in their life cycle, i.e. eggs, nymphs and adults. Nymphs look like adults except that they are smaller in size, do not have wings and cannot reproduce;
• Cockroaches can be found both indoors and outdoors ubiquitously where food is present;
• They prefer dark, warm and moist environment and love to hide in cracks and crevices;
• They are most active at night; and
• They are omnivorous but prefer starchy food.

Hazards Caused by Cockroaches

• Produce odorous secretions and have adverse effect on food quality;
• Carry pathogens on their surfaces which can cause disease including food poisoning, nausea, vomiting and diarrhea;
• Carry a wide variety of harmful microorganisms inside their body; and
• Contain a number of allergens, in their excrement and their cast-off skins, which can cause rashes, watery eyes and sneezing.

Measures to Prevent and Control Cockroach InfestationEmphasis should be on prevention as it is difficult to control once cockroach infestation has established.

1. Leave no food for cockroache

• Keep premises, especially kitchen, dry and clean
• Store food properly and remove pet food completely after feeding
• Put all refuse and food remnants into a bin with well-fitting lid. Contents of the dustbin must be emptied completely at least daily. Refuse bags should be tied up before disposal to prevent spilling

2. Eliminate Harbourage for Cockroaches

• Clean up refuse and unused articles especially old newspapers and magazines at homes;
• Inspect at least quarterly the bottom and back of furniture and concealed places like false ceilings, air ducts and wire ducts; and
• Seal any cracks and crevices at ceilings and on walls and floor

3. Stop Cockroaches from entering premises

• Install drain covers (without openings) which can be opened for the discharge of the drainage water. Replace them if they are found damaged;
• Seal all openings on external walls, floors and roofs through which pipes and wires pass or left by installation of split-type air-conditioners;
• Apply a band of petroleum jelly at least 10 cm in width around dry drain hole to prevent cockroach from passing through the hole; and
• Install wire mesh of 2mm at drain holes for preventing entry of Periplaneta americana.

4. Trapping

• Use sticky traps at places frequented by cockroaches. Whenever possible, place traps either against a wall or in a corner of a floor, a shelf or a drawer

5. Poisoning

• Use insecticide with residual effect for killing the pest by contact;
• Set poisonous bait to kill cockroaches. The bait will not only kill those cockroaches consuming the bait but also those in the harbourage indirectly;
• Caution must be taken when using insecticides. Follow strictly the application instructions on the label to avoid harming people and animals.

6. Handling of dead cockroaches

• Wear gloves when handling dead cockroaches.
• Areas or equipment including the gloves having contacted with cockroaches should be washed and disinfected with household disinfectant as soon as possible¡@

Enquiries

You may approach the Pest Control Sections of various District Offices (Environmental Hygiene) or the Pest Control Advisory Section of the Food and Environmental Hygiene Department for enquiries.