Dale Hudson of Syngenta Professional Solutions outlines the differences between the most common species of cockroach that pest managers will encounter.
Cockroaches are one of the most difficult pests to eradicate, due to their adaptability, their ability to quickly become resistant to insecticides, and their prolific reproductive habits. Whether indoors or outdoors, cockroaches are guaranteed to be in close proximity to any inhabited building in Australia.
As with any pest, correctly identifying the species is the key to gaining control. While German and American cockroaches are usually the main culprits, there are several other species – usually grouped as ‘other common cockroaches’ on insecticide labels – that it pays to be familiar with.
German cockroach (Blattella germanica)
These strictly domestic (indoor living) cockroaches are bronze-brown colored, with two dark parallel streaks or ‘racing stripes’ on the pronotum (below the head). They have long antennae, and the adults have wings but do not typically fly. Adults average around 1.5 cm in length.
German cockroaches have the highest reproductive rate of all domestic species, and they mature very quickly (within 45 days). German nymphs are more likely to survive than other species, as the female carries the ootheca/egg cases throughout the incubation, protecting them until hatching. German cockroaches prefer warm, moist areas.
Brown-banded cockroach (Supella longipalpa)
Similar to the German cockroach, the brown-banded cockroach averages 1.5 cm in length as an adult and is also a strictly domestic species. It has two light-coloured bands running across the base of its wings, and the nymphs have two light-coloured bands on their bodies, hence their name. The female can be a darker brown, and the adults of both sexes have wings, although only the males fly. Compared to other common cockroaches, they tend to prefer drier conditions such as bedrooms (especially in the cabinets and night tables), in wardrobes, behind peeling wallpaper, and inside electronic equipment.
American cockroach (Periplaneta americana)
Pest managers will know these by sight, as the largest cockroaches commonly encountered. Ranging up to 4 cm in length as adults, these large, red-brown cockroaches have a pale edge on the pronotum (just below the head) and the ability to fly.
They prefer dark, moist, warm areas, and are commonly found in restaurants, supermarkets, basements, and sewers. As a peridomestic species (living in and around human habitations, both indoors and outdoors), they often invade buildings through the plumbing system, with sewers being common breeding sites.
Australian cockroach (Periplaneta australasiae)
The dark brown Australian cockroach is similar in length (3-4 cm) and appearance to the American cockroach, but can be distinguished by a yellow band on the thorax and yellow along its sides near the wing base.
Unlike other cockroaches, this peridomestic species normally feeds on plants and will also feed on decaying substances. Common breeding sites include tree holes and palm trees.
Smoky brown cockroach (Periplaneta fuliginosa)
At around 4.5 cm long, the smoky brown cockroach is as large the American cockroach but has uniform mahogany brown colouring with no bands or stripes (unlike American and Australian cockroaches).
The adults are strong flyers and attracted to light. This peridomestic species is more arboreal, commonly found breeding in tree holes and palm trees. They will typically enter a home through the attic or upper levels of the building.
Brown cockroach (Periplaneta brunnea)
This is a large, winged species of cockroach that is dark reddish-brown in colour. The key distinguishing feature of the brown cockroach is its cerci, which are two pointed barbs or spines, found near the posterior end of some cockroaches. Brown cockroaches have a pair of blunt, short, dark-coloured cerci while American cockroaches have longer and sharp-pointed cerci.
A periodomestic species, they are commonly found breeding outdoors, typically in mulch.
Oriental cockroach (Blatta orientalis)
On the smaller side, with adults around 2.5 cm with short wings, these dark reddish-brown/shiny black cockroaches are peridomestic, surviving very well outdoors. They spend considerable time under debris where they feed on decayed organic matter.
They are likely to enter homes via pipes, vents, drains and openings into crawlspaces, basements and lower floors. If encountered inside, they are attracted to starchy foods.
Knowing the species is important for the pest manager, but the customer doesn’t care what type of cockroach is present. No-one likes a cockroach hanging around, they just want to see results.
When dealing with persistent cockroach problems, the best treatment option is often to use products in combination, such Arilon Insecticide and Advion Cockroach Gel. Each product is ideally suited for use in different areas in and around a building, so when used in combination a comprehensive treatment can be applied. Advion is best used in sensitive areas and around appliances, whereas Arilon can be used as both a broad area spray as well as targeting those hard-to- reach crevices cockroaches love to hide in.
The weighting of the two products and exact placement can be modified depending on the main cockroach species present. This makes Arilon and Advion a very effective and flexible combination, ideal in situations where superior cockroach control is needed, such as commercial kitchens, warehouses and areas with persistent infestations.
As Arilon Insecticide is non-repellent, it can be used in the same areas as Advion without worrying about contamination – using the two products together delivers a broader, longer-lasting treatment zone compared to just using one product alone.
Dale Hudson, Syngenta Professional Solutions