German Cockroach/Steam Fly – blatta germanica

 

German cockroach

 

Adult size (approx.): 1.2cm-1.5cm

Habitat

A nocturnal pest that tends to find warm, humid conditions.  Not a pest to be found outside in Britain but in heated buildings and heating ducts.  When inactive, Nymphs and Adults are found clustered together in harbourages attracted by a pheromone they release.  Harbourages are normally close to food and water sources.  They forage on a wide source of foods and need free access to water.  They are able to climb smooth surfaces such as walls.

Biology

 

Egg – Nymph - Adult
Egg: carried in a case called the Ootheca, each containing 30-40 eggs.  The eggs are carried by the Female for 2-4 weeks before hatching.
Nymph: the Nymph moults 5-7 times during a 2-6 month period when they reach maturity.  They live and feed with the adults.
Adults: the Adults are small and inactive.  Their colouring is a yellowish brown.  They have wings but do not normally fly, living approx 6 months.

 

Importance

They can carry disease organisms and are capable of spreading rapidly in the correct conditions, becoming a serious pest.

Control

An established cockroach infestation is likely to be difficult to control. This is because the cockroaches will be distributed throughout the building in difficult to reach harbourages. Furthermore the phenomenal breeding potential and production of many egg cases by each female cockroach means that unless a very high proportion of the population is eliminated, numbers will continue to increase.

An integrated programmed approach is essential. Spot treatments will be completely ineffective for all but a small, localised infestation.

Before a treatment is carried out, it is important to identify the cockroach species. This will provide details of the biology, life cycle and habits of the pest, which can be exploited in the control programme.

Monitoring the extent of the infestation by visual inspection of voids, potential harbourages and the use of traps will help identify hotspots of infestation. Inspections are best carried out at night when the cockroaches are more active. A torch fitted with a red filter should be used, as cockroaches do not respond to red light. Aerosols may aid in flushing out insects from their harbourages.

When using sticky traps, suitable placement sites would be underneath equipment, behind counters, in roof spaces and in ducting and electrical trunking.

As cockroaches become trapped, the trap becomes more attractive to other cockroaches because of the effects of aggregation pheremones exuded by the trapped cockroaches. Adjoining building and areas sharing services should be included in the monitoring.

Non-chemical control methods, such as removal of food and water residues, proofing, improving hygiene and creating access to difficult-to-reach areas, will all aid a successful cockroach control programme.

If chemical control is needed, a combination of different formulations for different areas will give the most effective treatment.

Care should be taken to select only those insecticides which are approves for use against cockroaches and that the area of approval covers the type of building to be treated.

Insect growth regulators, baits, residual insecticidal sprays, insecticidal dusts and ULV formulations may all be considered and most usually a combination of all or some of them will be selected. Use of one type of formulation alone in a complex building is unlikely to achieve a sufficiently high level of control. Re-treatment of all or some areas will almost certainly be needed. A thorough treatment is needed.

After insecticidal application, post treatment monitoring should be carried out and steps should be taken to prevent re-infestation, by attempting to determine the source of the original infestation.

For instance, are oothecae or cockroaches being introduced on incoming goods, laundry, potted plants or via drains?

Continued use of sticky traps as a permanent early warning system may also be useful.

Oriental cockroach/black beetle – blatta orientalis

Oriental cockroach

Adult size (approx.): 1.7cm-3cm

Habitat

A pest that enjoys warm environments but can also be tolerant to colder conditions.  Nymphs (young Cockroaches) and Adults, cluster in groups when inactive.  They forage on a wide range of foods needing access to water.  They can be found indoors in heated buildings, underground heating ducts, drains, refuse tips and externally near buildings.  They can survive outside over the winter period in sheltered conditions but are unable to breed.  They do not tolerate extremely hot and dry conditions.

Biology

 

Egg – Nymph – Adult
Egg: The eggs are carried in a case called the Ootheca approx per Female with an average of 16 eggs per case, being laid at intervals.
Nymph: the Nymph can moult from 7 to 10 times at this stage, taking 6 to 15 months to reach maturity.
Adult: dark brown in colour with partial wings/wing buds but are incapable of flying.  They are a robust Insect living up to 6 months.

 

Importance

The Cockroach can be a serious pest in heated buildings such as launderettes, hotels and multi occupational dwellings, particularly in urban areas.  The Oriental Cockroach has been known to carry disease organisms.

Control

A difficult pest to eradicate unless dealt with correctly.  Surveys should take place using monitors and possible night inspections.  A thorough treatment is needed to include a residual spray treatment with gel bait being placed in harbourage areas.  Repeat treatments may be necessary until total control or eradication is achieved.

Areas Covered for Cockroach Control

 

Cockroach Control Essex, London & Kent

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