Surprisingly cockroaches are close relatives of termites and belong to the insect order Blattodea and their origins are believed to go back at least 300 million years. There are about 3500 species of cockroaches worldwide, pest controllers in Australia tend to only deal with about 6 pest species. All of these pest species develop wings as an adult and can fly, where a lot of cockroaches do not develop wings in their life cycle. Female cockroaches will release pheromones to attract a male counterpart, eggs develop in the female and are encapsulated in a purse shaped egg case called in a ootheca. An ootheca can contain anywhere from 12 to 40 baby Cockroaches referred to as nymphs The egg case may take as few as 6 weeks too many months to hatch and is usually determined by the weather conditions where it has been laid. Nymphal development involves as many as 6 moults in some cases and adulthood can take from 2 months to over a year depending on the species, each female cockroach can lay between 5 to 30 egg casings depending on the species and her environment. A cockroach does have an omnivorous feeding habitat which style is very suitable around humans where it is very common that they will feed on our food scraps, kitchen benches and pet foods. They prefer to feed at night as they have less predators during this time however in an overcrowded environment they will be seen during the day.
There are a range of registered pesticides for the control of Cockroaches however specialist products are generally required for the control of German cockroaches due to their ability to avoid products or have a resistance to them. A general treatment would include permethrin dust in the roof void, sub floor and wall cavities with a liquid treatment internally and externally.
Why are cockroaches considered pests?
As previously stated cockroaches are happy living in and around a human environment therefore they can create contamination of food products utensils by feeding, faeces, egg casings or vomit marks on surfaces. In extreme infestations cockroaches will create a very unpleasant odour that can be enough to make someone want to vomit. While it has never been proven cockroaches are believed to carry diseases that can be transmitted which would be related to them infesting food preparation areas or other areas that require hygiene, they have been known to bite people but this is very rare.
German cockroach ( Blattella germanica )
German cockroaches are one of the smallest species and most successful at coexisting with in human buildings. They can take as little as 40 days to develop from hatching to adulthood and each egg may contain 30 to 40 nymphs, they are a light brown and have too dark stripes on the pronotum ( head ). German cockroaches are very common in commercial kitchens and are usually first located in around the kitchen area in a normal house and will then spread from there two areas where there is preferred warmth or tight crevices for harboridges and eventually if left untreated will take over the whole house, they are not commonly detected in the sub floor or roof void areas but like all pest cockroaches do have wings as a mode to set up new areas to habitat, however they are very easily bought in with boxes containing egg cases or nymphs or people purchase second hand appliances. Their favourite hiding places I usually behind the fridge, microwave or dishwasher, under the kettle or phone and in around your kitchen cupboards, it is not uncommon for electrical equipment to fail due to cockroach infestations. They are extremely resistant to certain products and have the ability to detect chemicals and avoid areas which makes it very hard to treat along with their fast breeding,until recently the best form of treatment has been with gel baits but with recent product development there are a couple of excellent liquid products on the market.
Brown Banded Cockroach ( Supella longipalpa )
The brown banded cockroach is the other small species that we tend to deal with in Pest Control, adults are pale brown in colour with very pale bands across the thorax and abdomen. An egg case will generally contain about 18 nymphs which will take two to four months to develop into adults, an adult may live for up to 6 months where a female will produce about 13 egg cases. They are a very active cockroach and very inclined to fly compaired to a lot of other species especially when disturbed. Unlike the German cockroaches they do not tend to plague areas as much and are more inclined to be seen individually and widespread through areas. Being on the wing at night makes it is very common to see the odd Brown banded cockroach about. they are generally very sensitive to chemicals and once contact is gained they are easily controlled, it is the fact that they tend to be a very mobile cockroach which makes them harder to control.
American cockroach ( Periplaneta americana )
The American cockroach is possibly the largest cockroach that infests houses or dwellings. Adults are a redy brown in colour with a pale yellow border around their body. Egg cases usually consist of about 16 nymphs and it take anywhere from 6 to 12 months to develop into adult hood, a female may produce up to 50 cases in her life span which can be 6 to 12 months as an adult. They are very commonly detected in roof voids, sub floors and in wall cavities of houses, commercially they do like to be around sewers, grease traps and other dark moist areas. It is very common to see them flying at night and have the odd one enter your house.
Australian cockroach ( Periplaneta australasiae )
The Australian cockroach is another of the largest species the body is a dark brown with a yellowish pronotum which will have to dark spots almost resembling glasses, the egg casings may contain up to 24 nymphs which may take 6 to 12 months to develop into adults where they will continue to live for another 4 to 8 months and each female can produce up to 20 egg casings. They to have very similar lifestyle as the American cockroach preferring the roof voids, sub floors and wall cavities of houses.
Smoky Brown cockroach ( Periplantea fuliginosa )
Smoky brown cockroaches are another relatively large species, adults are dark brown to almost black with no pale markings. Each egg case will have up to 26 nymphs which once hatched will take 6 to 12 months to develop into adulthood and will live for about 6 to 12 months as an adult, the female will produce up to 20 casings. Like the other large species they are seldom found in plague proportions inside houses, they much prefer the roof void, sub floor and wall cavities or the outdoors particularly around decks or pergola areas and retaining walls.
Oriental cockroach ( Blatta orientalis )
This is a medium sized cockroach which is dark brown to black, the female has much shorter wings while the male has wings that almost cover it's entire abdomen. Egg casings will usually contain up to 16 nymphs and may take 6 to 18 months to develop into adulthood which will last for about 3 to 6 months, where the female may produce up to 14 egg casings. The oriental cockroach does prefer the cooler conditions therefore is more of a pest species in the southern cooler parts of Australia.