Do Cockroaches Bite? Perth Guide to Three Species

Do cockroaches bite or sting?

Cockroaches do not bite. What they do carry is bacteria. Cockroaches walk through drains, sewers and refuse, then cross benches and food bowls. They may be a reservoir for salmonella, staphylococcus and streptococcus, and also harbour viruses such as polio. Their faeces and shed skins are a recognised asthma trigger in homes and workplaces. That is why food businesses run continuous management programs and why we treat the breeding sites inside voids and drains, not just the visible adults walking across your kitchen.

Close-up of a cockroach on a rock — A cockroach up close. Three species are common in Perth.

What are the three Perth cockroach species?

German cockroach (Blattella germanica): small, 12 to 15 mm, tan with two dark stripes behind the head. Lives indoors in warm, humid voids near food and water, especially kitchens. One female produces dozens of offspring per egg case and carries several cases over her life. More on removing German cockroaches.

American cockroach (Periplaneta americana): large, 35 to 40 mm, reddish-brown. Flies clumsily into kitchens late at night. Lives in drains, sewers, sub-floors and the gap behind the dishwasher where the drain pipe enters the wall. Can survive two to three months without food if water is available.

Australian cockroach (Periplaneta australasiae): similar size to the American, 35 mm, with yellow edges on the wings. Breeds outdoors in mulch, compost, wood piles and under pavers. Wanders indoors through gaps under doors and weep holes. Prefers plant material and can damage clothing and books. See also our full guide to cockroach removal.

How to spot cockroaches in a Perth home

Fresh droppings inside cupboards look like coarse ground pepper. Smeared brown marks along the top of cupboard doors are a sign of infestation. A musty smell in the pantry may be a sign. You may find empty egg cases, purse-shaped, behind appliances or inside kickboards.

Adults seen during the day are a sign of a large population. If you see one walking across the kitchen bench or the floor in daylight, the harbourages are full.

German cockroaches live in warm, humid voids near food and water: behind and under the fridge, under the dishwasher, and in pantry kickboards. Sticky traps placed near suspected harbourages can help monitor activity.

Why cockroach infestations build up fast in Perth

Perth's mild winters mean cockroaches do not die off seasonally. Cockroaches hide in cracks and crevices during the day and feed at night. German cockroaches live indoors in warm kitchens, bathrooms and around warm appliances. The German cockroach has three to four generations per year, taking as little as 40 days to develop from hatchling to adult, and can produce up to 20,000 young annually. This is why a single female can establish a heavy infestation quickly, and why gel bait and growth regulator, not spray alone, is the standard treatment.

What you can do yourself to reduce cockroaches

Remove water sources. Fix or report dripping taps and leaking dishwasher hoses. Water is the reason cockroaches chose your kitchen. Dry the sink before bed and wipe benches and under appliances.

Clean thoroughly and regularly. Empty kitchen bins daily. Do not leave pet food or bowls out overnight. Wipe up food spills immediately. Clean under the fridge, stove and toaster weekly. Vacuum regularly, especially corners and cracks where faecal pellets collect.

Reduce harbourages. Remove stacks of cardboard boxes, newspapers and magazines. Store food in sealed airtight containers. Seal cracks and crevices in skirting boards and around pipe penetrations where you can reach them.

Do not spray before calling a professional. Repellent aerosols scatter cockroaches away from gel bait placements and hide the harbourages we need to find. If you have already sprayed, tell us and we will inspect carefully before treating.

What not to do when you find cockroaches

Do not bomb or fumigate the kitchen with supermarket aerosols. Spray kills the cockroaches walking around, but the population inside wall voids, behind appliances and inside egg cases breeds back faster than the survivors die.

Do not rely on spray alone. Spray is the smallest part of a proper treatment. Gel bait reaches the cockroaches inside voids and walls, and an insect growth regulator stops juveniles maturing into breeding adults. Without these, you are treating the symptom, not the cause.

If you have already sprayed or bombed the kitchen, do not treat with gel bait immediately afterward. Repellent aerosols will scatter cockroaches away from the gel. Tell us what you have used, and we will advise the safe interval before gel placement.

Do not assume the problem will go away. Call for a treatment plan and a written quote.

When to call a cockroach management professional

Call when you see droppings, egg cases, or adults, especially in daylight. More are present and breeding in harbourages you cannot see. Text a photo to 0468 170 107 and we will identify the species and advise the next step.

We provide cockroach management that identifies the species, finds the breeding sites with a torch and flushing agent, places gel bait and insect growth regulator inside cabinetry and appliance voids, treats drains if needed, and includes a follow-up visit. For German cockroaches, a kitchen program includes inspection, gel placement, growth regulator, targeted residual, follow-up visit and a report, all applied to label by a technician holding a WA pest management technician's licence and carried out under the direct supervision of a licensed technician. Work is covered by our six-month re-treatment promise (terms at djpest.com.au/warranty): if the cockroaches we treated are still active inside the treated areas within six months, we return at no charge.

What cockroach treatment costs in Perth

Light cockroach activity within a general pest treatment is $250 to $350, typical range for a standard three-bedroom home in Perth's northern suburbs, itemised in writing after we have seen it. You get the price in writing before we book, and the treatment record after. See our full pricing guide for all pest types.

Frequently asked

Do cockroaches carry disease?

Cockroaches may be a reservoir for bacteria including salmonella, staphylococcus and streptococcus, and also harbour viruses such as polio. Because they walk through drains and refuse then cross food-preparation surfaces, disease may be transmitted to humans through contaminated food. Their droppings and shed skins are recognised asthma triggers and a reason food businesses run continuous management programs.

Can I treat cockroaches with supermarket products?

Supermarket sprays are repellent and scatter cockroaches away from gel bait placements. Some supermarket baits work if placed correctly, but repellent sprays should not be used beforehand. Always follow label directions exactly. If you have already sprayed, wait the interval the label specifies before placing gel bait.

How long does cockroach treatment take to work?

German cockroach activity usually falls away over two to three weeks as the gel and growth regulator work through the population. Drain-based American and Australian cockroach jobs clear faster because the breeding site is treated directly. A scheduled follow-up visit, included in the kitchen program, checks placements and applies more gel if needed.

Are cockroaches worse in spring?

American and Australian cockroaches come from outdoor breeding sites and move indoors. German cockroaches do not die off in Perth's mild winters.

What is an insect growth regulator?

An insect growth regulator is applied inside voids and works by preventing juvenile cockroaches maturing into breeding adults. We use non-staining products and apply them to label.

Will cockroaches come back from next door?

German cockroaches can move between units through shared walls and plumbing. Strata-coordinated treatment gives the best outcome. If only your unit is treated, we seal the penetrations we can reach and set expectations honestly in the report: pests can re-enter from next door, and the re-treatment promise (terms at djpest.com.au/warranty) applies within six months to cockroaches still active inside treated areas.

What is the difference between German, American and Australian cockroaches?

German cockroaches are small (12 to 15 mm), tan with two stripes, and live indoors in warm voids. American cockroaches are large (35 to 40 mm), reddish-brown, and live in drains and sub-floors. Australian cockroaches are similar size to American with yellow wing markings and breed outdoors. Each species requires different treatment: German jobs target cabinetry; American jobs treat drains and penetrations; Australian jobs address external harbourages and perimeter sealing.

Sources

Cockroach Control Perth, the full service and the investment
Pest management investment ranges in Perth, every service with a typical range
What's my pest?, pick what you saw
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