Pest Control

Pests We Treat

All Pest Control Officers have received recognised training and have very considerable experience to fall back on. The following notes summarise good practice.


Flies and Minor Insect Pests
Garden Ants

Bed bugs



The species of rat that is invariably found locally is the brown rat Rattus Norvegicus. The black rat (Rattus rattus) is far scarcer and only frequently found away from the channel ports. Unlike mice rats show a distinct neophobia or fear of things new. Accordingly bait shyness may be a problem when initially treating an infestation of rats.


The pest control officer will;

  • Inspect the site, identify harbourages and determine most appropriate course of action.
  • Determine whether the customer has young children and/or domestic pets.
  • Determine if a history of allergies/sensitivities exist.
Rats Inside a Dwelling

In this scenario the use of slow acting anti coagulant poisons such as Difenacoum or Brodifacoum would be the primary option. The following to be ensured:-

  1. That baits are positioned to eliminate or at least minimise risk to non target species i.e baits to be placed in closed cupboards, locked rooms or if in open rooms within locked metal bait boxes.
  2. Customer to be aware of location of baits and advised to keep children and pets away.
  3. Follow up treatment to be made within 10-14 days or earlier if requested by the customer. In certain instances a follow up visit may not be required - customers will be informed if this is the case.
  4. Baits and dead rats to be removed accordingly.
  5. Customers to be advised that they can dispose of dead rats in their domestic rubbish.
Rats in a Garden

Similar considerations apply to the above although the use of metal boxes and rodenticidal blocks rather than loose grain would be preferred.

Proofing and Housekeeping

In all cases if deficiencies with regards to either of the above are noticed these should be brought to the attention of the householder.


The use of traps for rats is not recommended owing to increased risk to non target species and the limited effectiveness of this approach.


The common mouse (Mus musculus) is a pest often encountered by homeowners. While rarely welcome mice do not produce the same abhorrence as rats although in terms of public health significance there is probably little to choose between the two. Whereas rats are wary mice are naturally inquisitive and will readily explore things which are new to them - such as mousetraps. The use of anticoagulant poisons is normally employed although conventional mousetraps, frequently baited with chocolate or peanut can be extremely effective when it comes to eradicating mice.

If traps are to be used the following should be ensured:

  • There are no toddlers in the house who could access the traps.
  • Traps are suitably located.
  • Follow up visits are made on a daily basis.

The advantage of using traps are:-

  • Rapid elimination of mice.
  • Humane - normally instantaneous despatch.
  • No risk from secondary poisoning.
  • Mice dying in inaccessible places avoided.

Advice v Treatment

At times of a particularly heavy workload it may be appropriate to advise customers to treat mice themselves on a DIY basis. If however the customer shows any reluctance to proceed on this basis a treatment will be offered. In all instance pest control advice is provided free of charge.

Flies and Minor Insect Pests

Advice on controlling a range of pests is given below.


House Flies and Blow Flies 

Both types of fly are very difficult to control as they can so easily enter buildings via windows and doors. Housekeeping is of prime importance in reducing the number of flies that you may find in your home. Cleanliness of work surfaces, kitchen utensils etc is essential as is ensuring that open food which will attract flies is not left out. Proprietary aerosol fly killers have their uses as fly swatters but the general use of insecticides to treat wall and ceiling surfaces is not recommended. The fly problem varies in intensity from year to year and regrettably is something that to a significant extent we have to live with.

Cluster Flies 

Whereas house and blow flies tend to occur in limited numbers cluster flies may appear within your home quite quickly in vast numbers. Cluster flies move in from the fields and gardens as the weather cools in autumn and may be found in attics as well as other parts of your home. If your home is affected by cluster flies then it is likely to be a recurrent problem which you may face every autumn. If the flies are found in concealed spaces such as an attic then the use of insecticidal smoke may be appropriate. Smoke bombs may be purchased from garden centres and general hardware stores. Products containing permethrin would be advised. As with all such products it is essential that you read the manufacturer’s recommendations and follow them very closely. Great caution have to be exercised if the dwelling rooms of your home are affected by cluster flies and in such cases employing the services of a professional pest control company would be recommended.


Silverfish are small, fast moving insects associated with damp conditions and frequently found at wall/floor junctions and under linoleum and other floor coverings. Spraying these areas with a residual action insecticide may provide some measure of control but unless the dampness is dealt with the product is likely to persist. Silverfish are however of virtually no public health significance.

Booklices (Psocids) and Stored Product insects 

Booklice are very small pale coloured insects which are barely visible to the human eye. They can however occur in very great numbers in bags of flour, pasta and other foods with a high starch contact. 
As with all pests of stored products such as biscuit beetles and grain weevils the essential requirement is to locate the infested food stuffs and to dispose of them. All items that have been stored in shelves and cupboards should be carefully checked as should the content of sealed containers. Thorough cleaning of all cupboards and the use of suitable sealed containers to store replacement stock would then be recommended. The use of insecticides to treat for these pests in domestic premises would not be recommended.


Fortunately cockroaches are only rarely encountered in Pembrokeshire but where they do occur heavy infestations may develop in a short period of time.

The two main species of cockroach encountered in Britain are:

The Oriental Cockroach (Blatta orientalis) 

The adult is a long very dark insect up to 35 mm in length. The female lays egg cases which contain up to sixteen nymphs or juvenile cockroaches. The developing stages of the cockroach are virtually immune to insecticides whilst in the oothecae(eggcases). 


Successful treatment involves thorough inspection to determine the full extent of the problem followed by a systematic programme of treatment using residual insecticides. 

A single treatment cannot be expected to control a population of cockroaches owing to the release of nymphs from the eggcases after treatment/spraying. 

Treatment primarily involves treating floors (and particularly wall/floor junctions) with a residual insecticide such as Ficam W or crackdown rapide. Dry holes and harbourages may be treated with dusting powder.

The German cockroach (Blatella germanica) 

This is a smaller more agile insect than the oriental cockroach which can in some parts of the Country be found in enormous numbers in catering establishments. The German cockroach is extremely agile and accordingly may make use of high level harbourages such as cooker canopies and the like. Unlike the oriental cockroach the female German cockroach carries rather than drops the egg case which may contain up 40 nymphs. 


Again one of the keys to success is determining from the onset the full extent of the infestation. The use of a flushing insecticide such as Insectrol is extremely useful in determining the whereabouts of German cockroaches. Treatment is very similar to that used in connection with oriental cockroaches although cracks and crevices harbouring cockroaches, often at high level may need to be diligently treated. This can be a messy process and the householder should be informed to this effect before treatment commences. Greater use is now being made of insecticidal gels which can be applied from a caulking gun.

Garden Ants

The species of ant most frequently complained about is the common black an (Lasius niger). Black ants are of very limited public health significance although the swarming of flying ants at breeding time in the summer can cause distress to some people. Garden ants may be effectively treated on a DIY basis.

Wasps (Vespula vulgaris)

Like ants wasps belong to the social insects or Hymenoptera. Wasps are generally not considered to be pests of public health significance although wasp stings are painful and wasps cause severe distress to many people. Additionally some individuals may demonstrate extreme sensitivity to wasp stings such that they may suffer anaphylactic shock as a consequence of being stung by a wasp.

Control Measures

The most effective method of control is to locate and destroy the nest as a whole. Thoroughly dusting the nest with an insecticide powder such as permethrin would normally be employed. Before pumping insecticide dust into any void or hollow harbourage every effort should be made to determine whether or not there will be a significant break out of product from the treated area.


Unlike wasps, bees are regarded as beneficial insects and accordingly there is general reluctance to eradicate bees. If a colony of bees is found in a dwelling or chimney however, then the distress involved to the householders may warrant control measures being employed. Smoke generators/bombs may be used in the control of bees.

Access to treat for bees can be a problem as sometimes there is a need to provide scaffolding or a hoist to allow for safe access. Unfortunately in cases such as this, the Council cannot meet the additional costs of providing safe access and the responsibility for this rests with the owner of the property. Thankfully, such measures are only necessary in a limited number of cases.

In addition to this, a recent court case has placed further restrictions on the Council's ability to treat for bees, as there is a requirement to prevent access to a structure that has been treated with an insecticide by other foraging bees, e.g. from local bee hives. This can be extremely difficult when a colony of bees is located in a chimney stack which may be inaccessible and where use of the chimney is required by the household.

The pest control officer will discuss all of these matters with you on site prior to carrying out any treatment.

Bed Bugs (Cimex Lectularis)

Bed bugs are thankfully rare in Pembrokeshire but they are a cause of some abhorrence to members of the public. Bed bugs are parasite insects which feed on blood. They emerge at night to feed on their hosts. Thorough treating of mattress seams, buttons, and tufts with a residual insecticide would be advised with all cracks, crevices, breaks in plaster etc adjacent to the bed also being treated. Consideration should be given in each case to the possible disposal of the infested bedding/mattress. In many cases when customers are informed as to the nature of the pests they may wish for no lesser course of action. Thorough spraying of the surrounding area once the mattress has been removed and destroyed would however be strongly recommended.


ID: 2304, revised 12/09/2023