Common Pests and Their Control and Prevention
Rats & Mice | Cockroaches | Flies | Bedbugs | Wasps & Bees
Rats and Mice
The risks
Both rats and mice are harmful pests, through gnawing, contamination, and disease. Their gnawing causes damage to packaging and property, and the failure of telephone and electrical systems. They can be the cause of otherwise unexplained fires. They contaminate food and food preparation surfaces as they explore.
Rodents spread parasites and disease, including Weils disease ( Leptospirosis ).
Rats
Rats (Rattus norvegicus ) vary in colour from brown to grey, with a light underbody. An adult weighs 400g – 550g, and typically lives for 12 months. They are able to breed from 3 months of age, and can have 6 litters a year with up to 10 young.
Mice
Mice (Mus domesticus) share the same colouring as rats but are much smaller, typically weighing 20g. In the wild they live for 3 to 4 months, and are sexually mature from 6 weeks. Litters have 4 to 8 young, and a mouse may have up to 8 litters a year.
Identification
Rodents are generally identified buy the damage they cause, because they are nocturnal and rarely seen. The damage can include gnawing damage to parts of a building and food packaging, spilled food, droppings, and the smell of their urine.
How they live
Rats and mice generally live on a vegetarian diet, but are actually omnivores: they will eat meat given the opportunity, including the bodies of other rodents.
Rats rarely nest indoors, so when a building is infested it is important to identify how they are entering, so that their route can be blocked. If there is a break in a drain or sewer they may use this as an entrance.
Mice will nest in any sheltered space. They are rarely found in drains and sewers.
They can enter a building through a whole one quarter on an inch square
Cockroaches
2 species are common pests in the UK : the oriental cockroach (Blatta orientalis) and the German Cockroach (Blatella germanica).
The seriousness of the health risk caused by cockroaches in commercial food premises may lead Environmental Health to impose compulsory closure.
The risks
Cockroaches carry and spread food poisoning organisms such as Salmonella, E-coli and Typhoid. They can also cause breathing disorders such as asthma.
They secrete an oily liquid, and leave excrement, that has an offensive odour.
Scientists believe that cockroaches leave chemical trails in their faeces, which other cockroaches will follow to discover food, water, and hiding places.
Identification
The Oriental cockroach is the most common species, and the largest. The adult grows to about 24mm long, is dark brown to black in colour, and can be shiny. They can climb rough surfaces such as brickwork.
The German cockroach is smaller, about 15mm long, and yellowish brown in colour. It is able to climb smooth vertical surfaces.
Lifecycle
Eggs are carried in egg cases ( ootheca ) which may be glued to solid objects or carried by the mother. The eggs hatch into nymphs, immature smaller versions of adults, and mature into adults over several months
Adults live up to a year in good conditions.
Cockroaches are omnivorous, and will even eat each other if there is no other food available. The cockroach is one of the hardiest insects. It is capable of living for a month without food.
Prevention
A high standard of hygiene will help reduce their food supply. Cockroaches prefer to spend the day hidden in warm, dark spaces, so these must be blocked off.
Cockroaches are nocturnal and hide from light, so infestations are not usually noticed until they are well established. It is usually necessary to use professional pest control experts.
Flies
The housefly (music domestic) is the most common pest occurring in homes and premises, and a spreader of disease and parasites.
The risks
Flies spread contamination with their legs and bodies as they move from their feeding grounds to food and food preparation areas. They also spread contamination because of the way they eat. Houseflies only can take in liquids, not solids. They spit out saliva on solid foods to pre-digest it, and then suck it in. They also vomit out partially digested food and eat it again.
Lifecycle
Houseflies begin life as eggs laid in garbage, faeces or food. After 1 day they hatch into white larvae (maggots) about 6mm long. The larvae transform into pupae, from which the fully-grown adult fly emerges. The adult fly is ready to mate 36 hours after leaving the pupae, and typically lives 2 to 4 weeks in the wild.
How they live
- Where do they go in winter ?
In the winter, flies survive in the larval or pupa stage in a warm hiding place - How do they walk on ceilings ?
Glands near their feet secrete a liquid onto the feet. The surface tension of the liquid holds them to the ceiling. - Why do they wash their faces ?
Flies continually preen themselves, cleaning their eyes with their forelegs and dusting off their legs by rubbing them together. They do this because most of their taste and smell receptors are on the hairs of their legs. - How can I catch them ?
- Flies have a very effective escape reaction which makes them hard to swat. Try clapping your hands several inches above the fly. It will instinctively jump into the air, usually into your closing hands.
Prevention
Covered, tidy refuse storage reduces the problem. Covering food and cleaning surfaces helps to prevent contamination.
In commercial kitchens fly screens and electric fly killers are necessary to protect food in preparation.
Bedbugs
The common bedbug (Cimex lectularius) is a small 6-legged insect that lives by feeding on the blood of humans and other warm-blooded hosts.
Bedbugs were almost eliminated during the 1950 and 1960s, by the widespread use of DDT. They are now making a come-back, with increased numbers of infestations being reported.
People can pick up bedbugs at hotels, and bring them home in their luggage. They can also come in with infested furniture or used clothing. Bedbugs may travel between rooms in multi-occupant buildings such as flats.
The risks
The bites can causes swelling and itching, but bedbugs do not spread disease.
It’s a myth that bedbugs are only present where hygiene is poor. They are attracted by carbon dioxide, not dirt, and they feed on blood, not waste. The cleanliness of their environments has no effect on them.
Identification
Bedbugs grow to 5mm, and are dark brown, with a redder colour after a feed. They are oval in shape and very flat, which helps them hide in narrow crevices. They are visible to the eye, looking a little like a lentil.
Signs of an infestation include small black dots on the bed linen, and the occasional red smear where a bug has been crushed while feeding. Because they stay well hidden during the day identification may require expert help.
Life cycle
Female bedbugs lay 2 or 3 eggs every day of their lives. The eggs are small and white or whitish/yellow about 1 mm long. After about 10 days a nymph hatches. The nymph is colourless, and is a small version of the adult, also feeding on blood.
How they live
Bedbugs are generally active only at night, and most active about an hour before dawn. They detect their hosts by warmth and the presence of carbon dioxide. As they feed they inject saliva, which contains anticoagulants and anaesthetics. After feeding for about five minutes, the bug returns to its hiding place. Bedbugs can live for up to 18 months without feeding, but typically seek blood every five to ten days.
Bedbugs are very flat, allowing them to hide in tiny crevices. They tend to group together. A crack wide enough to fit the edge of a credit card can harbour bedbugs. They stay out of the light, hiding in mattress seams, mattress interiors, bed frames, or bedroom clutter. They can travel up to 100 feet to find a host, but prefer to hide nearby.
Eradication
Thorough, professional treatment is needed as to get rid of bedbugs, because their hiding places are so diverse and difficult to detect.
Wasps & Bees
Wasps and bees are a well-know nuisance during the British summer. We all know their attraction to sugary foods and their painful sting.
The Risks
Beyond the painful sting, One per cent of people living in the UK have a life-threatening allergy to wasp stings. A sting can trigger a potentially fatal anaphylactic reaction with symptoms that include breathing problems and an extreme drop in blood pressure. In 2004/5 848 people in the UK were hospitalised following stings. There is advice from the BBC here.
Wasp Lifecycle
Queen wasps mate with a male drone then store the sperm cells inside their body.In early autumn most of the wasp colony dies, leaving only the young mated queens. The queens leave the nest and find a suitable spot to hibernate through the winter.
In spring the young queens search for a nesting site, then start to build their nest and lay eggs. The sperm that was stored earlier is used to fertilize the eggs being laid. A single female queen is quite capable of building an entire colony from only herself. The first eggs laid become sterile female workers who construct a more elaborate nest and feed the larvae.
Towards the end of the summer the queen lays eggs that develop into fertile males and fertile female queens. The male drones leave the nest to find a mate. The queens mate, then leave the colony to hibernate for the winter.
Each nest produces 200 to 300 queens of which 10% will survive the winter, giving the possibility of 20 to 30 new nests.
Points to note on wasps
- Wasps are of great benefit to farmers and gardeners because they kill large numbers of plant-feeding insects and nuisance flies.
- When someone is stung their body reacts by giving off a pheromone. Wasps detect the pheromone and are attracted to it.
- Our staff always wear protective equipment when removing wasps nests.
- Local councils now charge for wasp removal
Points to note on bees
- Honeybees are only a pest when a swarm lands in the wrong place. The swarm is a queen moving on to start a new colony, accompanied by her workforce.
- Honeybees sting only once, leaving a stinger imbedded in the skin.
- Bees are protected by the 1981 Wildlife Act. A swarm should be relocated, rather than destroyed, if at all possible.
