Dealing With Household Pests

There is a lot you can do to minimize the risk of insects or rodents encroaching into your home. The invaders seek food and warmth and are attracted by unhygienic conditions, so regular and thorough cleaning of all floors to remove food deposits and fluff is essential. Inspect the loft for dead birds and nests and clean out cupboards regularly.

You should never leave any food waste or other rubbish in the house — seal it in bags and put it in the dustbin. Keep the dustbin away from doors and windows and make sure it is kept clean and the lid is tightly closed; you should burn extra rubbish if the dustbin is full.

Fill any gaps in the structure of the house through which rodents could enter. Make sure the house is free from damp since this is a source of pest problems; inspect the underside of baths, the backs of sinks and other likely damp areas.

Even in the kitchen you should never leave food uncovered — keep it in sealed containers; kitchen surfaces and shelves may look clean but any deposit of a sweet substance, for example, could lead to an invasion of ants.

Types of pesticides

A selection of pesticides for dealing with insects and rodents is available in hardware stores, builders’ merchants and department stores. The applicators contain special chemicals and the most common of these used as domestic insecticides are: pyrethroids for flying insects; lindane, diazinon or carbaryl for crawling insects; lindane for moths and ants.

For mice the baits contain alphachloralose, calciferol or difenacoum. Branded products usually have names which are descriptive of their use, so you should have no trouble in finding a suitable product once you have diagnosed your particular pest problem.

Puff pack

This type is a soft plastic container with a capped nozzle enabling the powder to be puffed into crevices and cracks.


This may be used against flying or crawling insects and for mothproofing fabrics; it is also useful for spraying into cracks and crevices which may be hiding places for insects.

Hanging strip

This is used against flies and moths; the plastic strip is impregnated and emits a dichlorvos insecticidal vapour over a long period. Hang it in a room, but not over food or near work surfaces.


A plastic container is filled with granules impregnated with dichlorvos and often has a flap which limits the amount given off and enables the treatment to last longer. When the problem is very serious, the flap can be opened to its full extent. Bait This is used to poison rats and mice and sometimes insects. Rodenticides are added to foodstuffs known to attract rats and mice. The baits are either slow-acting, taking several days to kill the rodent, or they work quickly to put the rodent to sleep, then to death. You should always ensure any bait is left out of the reach of children and pets and follow the manufacturer’s instructions carefully. It is available in handy sachets.

Common Household Pests

1 Winged red ant

2 Bed bug

3 Adult carpet beetles and larvae

4 Fur beetle

5 German cockroach

6 Common cockroach

7 Earwig

8 Green bottle

9 Blue bottle, larva and pupa

Fairly regular holes in fabric seams are signs of beetle attack. Spray with carpet beetle killer or mothproofer and puff insecticidal powder into crevices and under carpets where fluff may collect. Cockroach There are two types: the German cockroach is 10-15mm (or I—iin) and the common cockroach is 20-40mm (or I—liin) long. You can distinguish it from the black beetle by its jerky movements and long antennae. Rare in domestic situations, cockroaches enjoy the warmth of heat.

Treating insects

Minor infestations can usually be treated with the branded products available. If the problem, from insects or rodents, persists or if it becomes a serious health hazard, contact your local authority health department. The department will have its own pest control officers or it may sub-contract to commercial pest control firms — which you may contact direct, if you wish. Some firms offer free advice on household pests and they will often identify any specimen sent to them — preferably in a tin box.

There are, however, remedies you can apply at home; these depend on thorough clearing-away of food wastes, dust and so on, so the problem will not reoccur.


Sweet foodstuffs attract ants; worker ants invade the house looking for food to take back to the nest to feed the larvae and queen. Try to find the nest and pour boiling water onto it as a first measure, then puff insecticide powder into it. Spray the thresholds of doors with insecticide. An alternative method is to put down a liquid or jelly bait near to the ant run; the worker ants will take the poisonous bait back to the nest and so poison the larvae and queen. When you put down the bait, the number of ants will increase; but after about two days the attack will die off.

Bed bug

This looks like a flat matchstick head, is brown and is usually associated with overcrowded, dirty rooms. Bed bugs are rare these days; but if they do invade, they will bite and cause severe irritation. Treatment must be left to the specialist with proper spraying equipment. Fumigation is rarely necessary.

Biscuit beetle

This is about 3 mm long and reddish brown and has a varied appetite — from biscuits to meat. Spray insecticide over surfaces and into crevices after cleaning out infested food. Carpet beetle It resembles a ladybird but has a mottled brown, grey and cream coat; it is 3mm long. A relative is the fur beetle, which is black with a white spot on each wing. It is the larvae which do the damage — they are covered with brown hairs and will curl up if disturbed. They emerge only at night in search of food. Cockroaches contaminate food, utensils and work surfaces and carry diseases, including serious food poisoning. Specialist help is essential in a serious or persistent outbreak, but the isolated case may be treated with long-lasting insecticidal killer sprayed into all possible cracks and hiding places.

Ground beetle

This type can grow up to 25mm (I in) long and is often confused with the cockroach. The beetle is harmless and normally only an occasional wanderer will come into the house from the garden. Spray insecticide powder over thresholds.


This is about 10-15mm (or I—in) long and enters the house via flowers or wall climbing plants near to windows. Dust corners with an insect killer and cut back any vegetation.


Infestations are usually a result of animals, especially cats — their fleas will bite humans. Attacks reach a peak in August and September, although central heating may mean they last all year round. Treat the animal with veterinary insecticides containing lindane or diazinon, available as shampoo, spray or powder. Treat skirtings and floorboard crevices with powder; aerosols for crawling insects may be used. Pay particular attention to carpet fluff and the animals’ sleeping areas. Persistent problems must be dealt with by an expert; check with your local environmental health department, which may offer a free fumigation service.


The most persistent and greatest nuisance in the home, flies, including bluebottles and green-bottles, contaminate food and cause diseases including food poisoning. Keep the house clean and always keep food covered; fit open windows with a wire gauze or plastic mesh fly screen. Aerosols or hand sprays and suspended impregnated plastic strip or a container should be used. Spray the dustbin with insecticide.


The two most common types are the brown house moth (with pale, golden wings) and the white-shouldered house moth (with mottled wings and shoulders). It is their grubs that eat holes in jumpers, carpets, upholstery and other fabrics, although man-made fibres have reduced the problem in recent years. Keep garments clean — moths like dirty clothes with perspiration or urine stains. You should store clean woollens in polythene bags tightly sealed with a moth repellent inside; hang moth repellents in wardrobes and vacuum your carpets regularly — especially the edges. Clean out drawers and shelves regularly. When you notice signs of attack, use an aerosol mothproofer; pay particular attention to seams and folds.


This is about 13mm long and silver- grey in colour. It usually emerges at night from a damp hiding place such as a bath, sink or at the bottom of a bread bin and eats starchy substances and carbohydrate food deposits. Although harmless. Its presence does indicate damp in the house. Check for silverfish behind sinks and baths and remedy the cause of the moisture; spray with insecticide or puff with powder.


This is harmless, but may cause extreme fear especially for those suffering from entomophobia. You can kill spiders by spraying or puffing with insecticide, either directly onto them or into their hiding places, but remember they do help control the insect population and therefore need not be removed.


The wasp attack reaches its peak in August. Wasps, which will sting if threatened, enjoy sweet-stuffs, so again cleanliness and hygiene is important. Place a fiyscreen over an open window or door to prevent entry and kill wasps with an insecticide aerosol. A nest of wasps should be treated at dusk when all the wasps have returned for the night; wear gloves and puff wasp nest killer into the entrance.


This is 10-15mm and has an oval, grey segmented body; one species rolls up when disturbed. Woodlice are normally found in the garden under stones and plants; if they do enter the house, they enjoy dark cool corners or the space under the doormat. Sometimes they will leave the house without any treatment; if they persist you should check and remedy the cause of dampness and cut back vegetation near the home. Look especially for any rotting wood on which they like to feed. Puff or spray insecticide around thresholds.

Treating rodents

There are two common types of mouse found indoors: the grey house mouse and the field mouse, which has a brownish coat, white underside and longer tail and ears. Mice will enter the house through cracks looking for food and shelter; they often stay and build nests — and will soon multiply. Because they nibble anything to keep their teeth worn down, electric cables and water pipes are often at risk. The presence of mice is indicated by chewed materials and dark coloured droppings. Mice transmit various diseases including food poisoning, so block all entry points and enforce stringent hygiene. Traps set with raisins or chocolate are not highly successful, since mice do not follow set runs. Mice have also become immune to warfarin poison. New forms of mouse-killer based on alphachloralose or calciferol are supplied in sachets; place the contents where you find evidence of a mouse. If the attack does not eventually cease, you should seek expert help.

Rats from dirty surroundings can bring serious disease and food poisoning; they also cause damage because of their constant need to gnaw. The most common is the brown rat, weighing about 500g (or 11b); it is 230mm (9in) long with small ears and a tail shorter than its body length. Black rats are normally found only in seaport towns; these weigh about 250g (or 8oz) and are slightly shorter than the brown rat. The rat is easier to poison than the mouse because it follows the same run, close to fences and skirtings. Place a sachet of bait along the run and keep replacing bait until no more is taken. You can then assume the rat has died. You can take the precaution of not leaving bread on the ground outside for birds — place it high up on a bird table or in a hanging basket. Block off any likely entry points into the house or sheds. Any serious or persistent problems must be dealt with as soon as possible and you should seek expert advice.

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