Organic Strategies for Cockroach Control
© Frances Michaels
Australia has many species of cockroaches, some of which are native and cause no problems. The German, American,
Australian, Smoky Brown and Oriental cockroaches are considered pests because they live indoors. Cockroaches
have not yet been proven to be involved in the transmission of disease, but the potential definitely exists.
Most cockroach species live for 3 to 12 months and take only 6 weeks to reach adulthood. Depending on the
species each female can lay 13 to 50 egg cases, each containing between 16 to 40 eggs.
The key to long-term cockroach management is reduction of sources of food; water and the shelter cockroaches
need to survive. Spraying of insecticides is a potentially toxic and short-term measure.
Proper Storage of Food
Food should be kept in tightly closed containers that are unable to be chewed by cockroaches. Cardboard boxes
should not be considered cockroach-proof. Sealing food containers will also reduce any health risk associated
with cockroaches. Any pet food should not be left out overnight. If necessary place it in a bowl of soapy water
to prevent cockroach access.
Storage of Organic Waste
Compost buckets need to have tight fitting lids; this also reduces fly and ant problems. Bottles, cans and
wrappings that have food particles clinging to them should be washed out before storage for recycling.
Screening for Vents and Windows
This is especially important in high-rise buildings and home units, as unscreened vents and windows allow the
cockroaches to crawl from one apartment to another. Place door seals on the bottom of doors to ensure that
cockroaches cannot enter. Eucalyptus oil can be used to repel them.
Fix dripping taps and leaking pipes, as cockroaches need water and humidity to survive. Try to remove unnecessary
containers of water, such as trays under pot plants as these will also breed mosquitoes.
A vacuum cleaner is useful to remove crumbs from corners and cracks in the floor, as well as inside cupboards.
It will also suck up egg cases. The dust inside the vacuum cleaner blocking their breathing apparatus will kill
most cockroaches. Regularly 'spring cleaning' behind stoves and fridges, to remove accumulated grease is
important. When there isn't time to wash the dishes, submerge them in soapy water.
Cockroaches can hide in cracks only 1.5mm wide. Seal as many cracks as possible, paying particular attention to
areas that the trapping program has highlighted.
Many conventional insecticides are ineffective against cockroaches. There are two main reasons for this. Sometimes
the chemicals used are repellent to cockroaches, so they escape its effects by moving away from it into wall
cavities for a few days. The second reason is that cockroaches have developed resistance to many insecticides.
If you make the permanent changes to the cockroach environment outlined above, you are more likely to get the
results you want when you do use an insecticide. There are three types of least-toxic chemical controls available:
insecticidal dusts, insecticidal baits and insect growth regulators. An important factor to bear in mind about
these materials is that they take a week or longer to kill large numbers of cockroaches.
Boric acid is a colourless, odourless, white powder that is slightly soluble in water. It acts as a stomach poison
to cockroaches when ingested. Borate products have low toxicity to humans and other mammals. When ingested in high
doses, however, boric acid can be harmful, single doses of 18 to 20 grams in adults or 5 to 6 grams in children
have been lethal. Therefore it must be kept away from food, children and pets. When inhaled, boric acid powder can
irritate the nose, throat and lungs. You should wear a dust mask, gloves and eye protection when applying it. Keep
boric acid in its original container and store in a safe place.
A series of studies (W.Ebeling, University of California) testing the effectiveness of common insecticides used
against cockroaches found that boric acid is less repellent to cockroaches than chlorpyrifos and other common
insecticides. It is also less repellent than borax, sugar or flour so it is best used alone. Boric acid is more
toxic to cockroaches than borax, and is picked up more readily due to its electrostatic charge. It can take 5 to
10 days before the cockroaches die. Although slow acting, it is certain to work. If you keep the boric acid dry,
a single application will continue working for many years.
To be most effective, it should be applied as a very thin film on the target surface. The dust should be barely
visible. If it is applied properly the cockroaches walk through it, rather than around it, and pick up the powder
on their legs, antennae and bodies. Their habit of frequent grooming leads to ingestion. Trouble spots underneath
the stove, refrigerator and cabinets should be given special attention. Dusting large open areas is less effective
than crack and crevice treatment. Solutions of boric acid in water can be used to mop floors to help with cockroach
Buzz cockroach traps
important monitoring tool, allowing you to identify the extent and location of the problem. Traps should be placed
in drawers, cupboards, under sinks and stoves and behind fridges. Cockroaches prefer to move along walls rather
than out in the open, so you need to place traps accordingly. Traps are useful in several ways:
Orange Guard Crawling Insect Spray
Buzz Cockroach Traps
- determining the areas with the worst problem
- confirming whether your management strategies or chemical controls are working
- with small infestations they can help to control numbers