Hygiene is the single most important factor in managing cockroach problems. Making access to food and water difficult constrains their normally high population growth.
Older buildings can be troublesome because old plumbing piping and equipment can leak and create damp conditions ideal for cockroaches. Fixing leaking equipment and sealing access points that allow cockroaches entry to the home are important steps in reducing cockroach numbers.
Doors and windows should be kept closed or screened at night to prevent cockroaches being attracted to lights and simply flying in.
Other common sense methods to reduce cockroach problems include:
- Cleaning food-contaminated surfaces like benches and plates and not leaving them dirty overnight.
- Reducing water availability overnight, mopping up puddles and fixing dripping taps and seals around sinks.
- Storing food in tightly closed, cockroach-proof containers.
- Inspecting incoming food for egg cases.
- Storing rubbish in tightly closed containers.
- Filling cracks and crevices that can act as shelter.
- Inspecting and cleaning surfaces below food processors and toasters.
- Cleaning ovens, cupboards and shelves.
- Avoiding dropping crumbs and spilling sweet drinks in the vicinity of computers and keyboards.
If chemical control is used, apply the chemical to ensure that the target insects have contact with it.
Surface-sprays are residual and should be applied to cracks, crevices and voids that may serve as a home for cockroaches. Pay particular attention to rubbish bins and receptacles. The bases of bins can be treated to ensure cockroaches contact the insecticide on their way to gaining access to the bin contents.
When treating cupboards, treat all the internal angles so that cockroaches must contact the treated surface when moving from a shelf to a wall and vice versa.
For German cockroaches, apply the spray to the undersides of drawers and shelves. Do not treat surfaces where food is handled and which regularly get washed down. If storage areas are treated remove food before treatment and replace after the treatment has dried. These surfaces may stay insect-active for months. Surface-sprayed insecticides usually act on contact as the insecticide is absorbed by the insect through the cuticle.
Spray around rubbish bins, sewer and drain inspection grids and house access areas like doorways and windows. Suitable surface sprays include the synthetic pyrethroids containing deltamethrin, imiprothrin and cypermethrin, imiprothrin and detamethrin, alpha-cypermethrin, bifenthrin and esfenvalerate and beta cyflurin with the systemic neonicotinoid imidacloprid.
Dusts contain permethrin and are used where wet sprays can be a problem and should be applied lightly. Dusts are useful near electric wiring, and where there is no likelihood of humans disturbing the dust deposit, such as in roof spaces or wall voids. Depending on the dust used, it can give months of protection.
Baits and traps can control small infestations but are usually more effective if used in conjunction with other types of management methods. However, ensure that sprays do not contaminate baits as this will make the baits repellent to the cockroaches and therefore ineffective. Baits contain indoxacarb, abamectin and fipronil and should be placed in corners and along edges (not treated with insecticide) where cockroaches travel. Traps are useful to monitor cockroach infestations as they can indicate their presence and level of activity.
Insect bombs can also be used to control cockroaches. Remove plants and pets from the home and cover fish tanks and food that can be contaminated by the sprays.
After setting off the bomb all residents should immediately leave the house for the time period specified on the product label. Follow the label's instruction on airing the home on your return and wait the specified period before moving back into the home.
Insect bombs contain products including permethrin and fenoxycarb and can penetrate areas you are unable to reach.
Control by natural enemies
Natural predators of cockroaches are various arthropods (including spiders), frogs, lizards, birds and mammals. Some wasps parasitise cockroach egg cases.