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Life Cycle & Description

Description of Oriental

(Blatta orientalis)


Primarily nocturnal, a pest of warm environments but tolerant of colder conditions. Nymphs and adults cluster in groups in harbourages when inactive attracted by aggregation pheromone. Forage on wide range of foods but need access to free water. Found indoors in heated buildings, underground heating ducts and also in drains, refuse tips and outdoors near buildings. May even survive winter outside in protected environments but will not breed below 10 °C. Climbs rough surfaces and may reach upper floors via vertical ducts, lifts. Does not tolerate extremely hot and dry conditions.

Egg – nymph – adult.
Eggs – in ootheca (case) about 5 per female each containing average 16 eggs, laid at intervals. Deposited when fully formed in harbourage. Incubation time 6–12 weeks, longer if cool.
Nymphs – 7–10 moults taking from 6 to 18 months to reach maturity. Live and feed with adults.
Adults - dark brown, robust, living up to 6 months. Partial wings or wing buds, incapable of flight.

Serious pest in heated buildings such as hotels, laundries, institutions and multi-occupation dwellings, particularly in large urban areas. Can carry disease organisms.

Difficult to eradicate and planned, proactive approach essential. Allowance must be made for the long incubation period of the treatment - tolerant egg case. Survey using monitors and night inspection. Wide range of products available including baits, dusts, residual sprays. Choose products with persistence and suited to conditions. Find and treat all harbourages. Repeat treatments and monitor until control achieved.

Distribution and Habitat

Very widely distributed worldwide, through the tropics and into temperate zones. The species occurs commonly throughout Britain, and mostly indoors in heated buildings. It is frequently associated with restaurants, hotels, laundries, hospitals, prisons and other institutions, old tenements and housing estates. May also occur outdoors around drains, dustbins and rubbish tips. Primarily nocturnal, although population pressures in outdoor infestations may produce some daytime activity.


The mated female lays up to five dark-brown egg cases or "purses" (oothecae), from which hatch up to 16 nymphs several weeks later. With an incomplete metamorphosis, they are miniature adults in form, and grow by several skin moults. The late-stage nymphs show "wingbuds". All stages are omnivorous though preferring starchy and sugary protein-rich foods, and need access to free water. They hide by day, often gregariously, producing a characteristic sour smell from their faecal deposits (these probably act as an aggregation scent), and nymphs and adults forage at night. The development from egg to adult can take from 6 to 18 months, depending mostly on temperature. The adult cockroaches can live for up to six months.


The Oriental cockroach is known to carry some pathogenic bacteria, although direct evidence for disease transmission to humans is scarce. The incidental damage caused by fouling and tainting of foodstuffs and non-food materials (e.g. sterile hospital supplies) is of greater financial significance. There is almost no tolerance within British society for the presence of cockroaches, and infestations in commercial restaurants and institutions are taken very seriously by Environmental Health departments.


General considerations:
There has been a tendency in the past to tolerate cockroach infestations, particularly in old premises with poor structures. However, with modern materials and with proactive strategies, eradication is possible in the great majority of situations.

Effective control of B. orientalis is is generally difficult to achieve due to the potential of emergence of immature stages from aged ootheca. Accordingly, repeat follow-up treatments should be made to ensure a sufficient level of insecticide is present to control emerging nymphs for up to, say, three months. Particular care should be taken in surveying outside infested buildings, especially drains, other underground ducting, and dustbin or waste food areas. Populations of B. orientalis is have been detected up to 80 yards from main building structures .
Although B. orientalis is does not climb as well as the German cockroach, it is able to climb rough surfaces easily and this should be remembered, during both survey and treatment. It has been known to reach up to the roof level of tower blocks probably via vertical ducts or lift shafts. In some situations, for example where monitoring devices are not used in numbers, night inspections may assist in determining the extent and/or main sources of infestation, particularly the exact location of harbourages, which may not be possible by the use of traps alone

–    A proactive control programme based on the use of cockroach monitoring traps, backed up if possible by occasional night inspections, is very important for the successful control of the
–    Oriental cockroach. Check also for signs of cockroach activity including live or dead cockroaches, egg cases, faecal smears around harbourages and, where infestations are heavy, the characteristic sickly sweet smell. A pre-treatment survey should be carried out before the control programme begins.


The thoroughness of treatment is all-important. The majority of products cleared for cockroach control are effective cockroach killers if they can be brought into contact with the insects. An integrated approach using a number of different formulations is essential against such a difficult pest.
The treatment of harbourage voids using specialist application equipment is vital in any control 
programme .
Bait formulations containing hydramethylnon, fipronil, imidacloprid and abamectin as gels have now become the first choice method for the control of cockroaches. Abamectin is also available as a flowable powder.
Surface sprays can be used in adjacent premises or rooms to intercept wandering individuals and include fenitrothion, chlorpyrifos (both available as microencapsulated formulations), residual pyrethroids and bendiocarb.


Description of

German Cockroach
(Blattella germanica)

Primarily nocturnal and a pest of warm, humid conditions. In UK only in heated buildings not normally outside or in underground heating ducts. Nymphs and adults cluster in groups in harbourages when inactive attracted by aggregation pheromone. Prefer narrow harbourages close to food and water source, Forage on a wide range of foods and need access to free water. Can climb smooth surfaces

Egg – nymph – adult.
Eggs – in ootheca (case) each containing between 30-40 eggs. Egg case carried by female for 2–4 weeks until just before hatching.
Nymphs – 5–7 moults taking 2–6 months (average 3 months) to reach maturity. Live and feed with adults.
Adults – small, active, yellowish brown, living average 6 months. Winged but do not normally fly.

Serious pest of heated buildings where it may rapidly spread if conditions are suitable. May carry disease organisms.

Requires very thorough planned treatment but may be easier to eradicate than Oriental. Survey using flushing aerosols and monitors. Choose suitably tolerant products when treating greasy, hot environments and re-treat as required. Use of bait applications in voids and harbourages. Sprays useful in adjoining areas.

Distribution and Habitat

The German cockroach is found widely throughout temperate climates and all of Europe. It seems to have been fairly recently introduced into Britain, some authorities stating that this occurred around the time of the Crimean War. In Britain it is a pest of warm indoor environments, especially institution heating systems and bakeries, and is known as the steamfly for its liking for the condition found in galleys on coasters and ocean-going ships.


The mated female cockroach produces a complicated egg-containing structure called an ootheca, containing a variable number of eggs, up to a maximum of about 40. In contrast to the Oriental cockroach, the German cockroach carries the ootheca attached to her abdomen up until the young nymphal cockroaches are about to hatch from the eggs and burst out of the seam of the ootheca. The period for this development is variable according to temperature, two to four weeks being normal.

The freshly hatched nymphs are white, but rapidly darken to a medium brown and undergo a variable number of skin moults, generally averaging six or seven. At each moult the insect grows slightly larger and gradually comes to resemble the adult insect, by increasing the antennal length, and developing increasingly large wing buds. Because of this incomplete metamorphosis, minor or even fairly major injuries early in the nymph's development can be repaired and regenerated during subsequent skin moults, but this tends to increase the total number of moults and time taken.

The adult cockroaches emerge from the final nymphal stage between two and a half and six months later, and are sexually mature. They are gregarious, and eventually produce sizeable population groups that, in turn, create a strong sour smell from aggregation pherornones and defaecation. They are not active during the day, but emerge in the dark to forage for suitable food and water. Since they need a free-water source for drinking, they invariably hide during the day in the vicinity of taps, sinks, drains and other water sources. They are omnivorous and will scavenge on any form of organic material, including human waste products. Warm conditions are required for optimum breeding, around 30 °C being ideal. They are fairly resistant to cold temperatures, although continuous exposure to frost is fatal.


The German cockroach is known to carry and spread various human disease organisms. Its habit of walking over and feeding on putrefying waste materials, drinking at unsavoury water supplies, and then freely walking over food preparation areas, cutlery and crockery, and human foods in its search for further food enables it to spread many disease organisms. In addition to this obvious problem, there is the added factor of human revulsion at the thought and sight of large numbers of cockroaches appearing unexpectedly when darkened kitchen and other areas are illuminated suddenly at night. The rapid scurrying and running action of cockroaches is upsetting, and the presence of so many insects may not even have been suspected by the owners or occupiers of the premises


This pest should be easier to eradicate than the Oriental cockroach because of the prompt emergence of its nymphs from the oothecae. In carrying out treatments against B. germanica , harbourage areas at some height above ground level should be treated in view of their climbing ability .
The use of baits based on hydramethylnon, fipronil, imidacloprid or abamectin together with residual sprays and dusts will control the majority of infestations, particularly if the insecticides can be introduced into harbourages and deeper voids. Use a crack and crevice attachment for water based sprays.

See also 'Control’ section under Oriental cockroach for further advice on cockroach control. In general, cockroach monitors are not as effective against German cockroaches as Oriental cockroaches, and it is important to thoroughly inspect all areas with the help of a flushing pyrethrin aerosol spray.    

If your having issues with Cockroaches or any other pest related problem within your commercial or domestic property then please feel free to contact us on 01282 777549 or email us at for an immediate response.

We are the leading service provider for pest control services in Burnley and Lancashire!

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