The real problem with both rats and mice is that they contaminate more food than they eat. Many diseases can be transmitted by both rats and mice, and their gnawing of cables and wires can cause electrical fires.
There are a number of species of these rodents in the major population centers in Australia. During winter, most rodents move indoors for both shelter and food. In commercial premises, these can be year round problems. In rural Australia, mice can attain plague proportions given certain climatic conditions.
The female will give birth to 4-6 litters a year, which will contain 5-10 young. These young can reproduce three months after birth, so it is calculated, that within one year, a single pair of rodents can be responsible for as many 400-700 pests
Are Rats & Mice at your premises
• Spreading diseases
• Creating foul odours
• Chewing through electrical wiring or wood
• Contaminating human food
• Causing serious damage to buildings
• Building nests and burrows
• A large nuisance to everyone in your home and office!
Identification
Rodent activity is usually at night, so it is important to identify these pests from signs they leave. An expert from Pestfree will professionally identify the specific rodent and likely nest location. It is important to get expert advice for effective eradication, as both rats and mice have a highly developed sense of smell and can often identify chemicals in food, warning them off domestic baits.
Solving The Problem
The Pestfree inspector will identify the type of rodent, and recommend suitable treatment and warranty for all work.
• Baiting to roof void and subfloor area.
• If internal problems lockable mouse and rat boxes are available.
Rats and mice are serious pests of humans, and they can, in some cases, be difficult to control.
These animals are well adapted to living in very close association with humans, sharing their food and shelter.
The rodents that are of great concern in the urban pest control context, not just in sydney, but in many countries, are:
• Norway Rat
• Roof Rat
• House Mouse
Throughout history, rats and mice have been responsible for enormous losses of food and, owing to their ability to transmit disease to humans by a variety of means, enormous losses of human life.
Whether it be crops in the field or foods in store, rats and mice still consume or contaminate vast amounts of food, and they can still pose a serious threat to health.
Urban pest controllers expend much time and energy in trying to control these very cunning and often cautious pests, which have so successfully exploited urban environments.
Biology and Habits
The distribution and abundance of pest rodents are largely determined by the availability of food and shelter. Rats and mice may live and nest within buildings indefinitely, provided they have access to food (perhaps water) and shelter. Often rodents will enter and nest in buildings only seasonally. In such cases, the rodents may begin to investigate buildings in Autumn or Winter, for if a suitable nesting site established with a food source within reasonable range, the somewhat warmer nesting conditions may facilitate more productive breeding. Alternatively, rats may enter buildings owing to a change in the availability of food. Rats feeding in school premises, for example, may cause problems in adjacent buildings during school holidays.
Being basically social animals, rats and mice live in groups, in nests constructed of any soft materials available (eg. paper, fabrics, insulation). Outdoors they may nest in burrows adjacent to waterways, under buildings and so on, in trees and vines, in garbage dumps, rubbish heaps and other places where food and shelter are within reasonable range. Indoors they may construct nests in wall voids, in rood voids, under floors and even within stored foods.
Rats and mice are generally regarded as very adaptable, omnivorous scavengers. They are very agile animals and mostly nocturnal, but they may range and feed during days, particularly if the population is very large, food is short, or there is little disturbance or danger. In their movements to and from the nest site, they are very sensitive to, and wary of, their environment. In their travels, they tend to move and feed under or near cover, seldom running out in open spaces. This behaviour displays a marked reliance on the sense of touch and is much exploited in the placement of baits and traps.
Rats, in particular, are very much creatures of habit, tending to use the same routes of travel to and from food sources for as long as possible. They are sometimes referred to as being neophobic, suggesting they have a fear of new objects (or other changes) in their otherwise well known environment. This behaviour can be the cause of their apparent disinterest in a new bait station, at least during the first few days of its appearance.
Mice, on the other hand, although seeming to maintain a high degree of caution in their movement, are very curious and adventurous animals. Mice often investigate new food sources within a very short time after their appearance, and they seem to prefer nibbling at small amounts of food at numerous different locations. This preference for feeding at several sites is often taken into account in mouse baiting programs.
Rats and mice are competent climbers and can scale rough walls, pipework, trees and vines; in some cases tight-rope walking across cables and the like is easily achieved. Rats (especially Norway Rats), are very accomplished swimmers. They have fairly earned the reputation of being able to negotiate the S-bend in toilets, a feat that no doubt caused alarm and personal discomfort over the years.
When at rest, rats and mice often groom themselves, licking their fur and feet. This behaviour is exploited when toxic powders are put down on surfaces from which the rodents are likely to pick them up. As well, they constantly gnaw at a variety of materials, but because their mouth and teeth are structured so that gnawings need not be ingested, this behaviour has little application in control measures.
The senses of rats and mice are mostly very keen, with the exception of sight.
In summary:
Sight – poorly developed. They cannot determine images sharply.
Smell – very keen. They use odour trails and can detect strange odours in foods.
Taste – very keen. They can detect strange tastes and may associate ill-feeling with certain tastes and/or smells in food. This may cause ‘bait shyness’.
Hearing – very keen. Their hearing range extends into the ultrasonic range.
Touch – very keen. As they are mostly nocturnal with poor eyesight, there is much reliance on the sense of touch.
Touch sensors consist mostly of nerve endings at the base of the whiskers and of long guard hairs on the
body – hence their tendency to move along vertical surfaces, which afford some protection.
Some biological control of rats and mice is effective when they are preyed upon by cats, dogs, snakes and some bird species.
Rats and Mice as Pests
The presence of rats and mice in buildings is usually regarded as undesirable from the viewpoint of food spoilage and contamination, physical damage, and the transmission of disease to humans.
Eating and contamination of stored foods
Rats and mice are responsible for enormous losses of food in store, either by directly eating the foods or by rendering them inedible through contamination. As the rodents move in and around stored foods, they contaminate the food with droppings (of which often more than 50 per day are produced), urine (which tends to be sprinkled on surfaces over which they travel) and hairs. At times, poultry may be killed and eaten by rats.
Gnawing: Physical Damages
The constant gnawing of rodents can be the cause of serious damage to a range of materials. Typically, they may damage doors, skirtings and other parts of buildings, upholstery, books, food containers or packaging, and parts of equipment or machinery. The gnawing of wires and cables has caused the breakdown of telephone systems and short circuiting, which may result in equipment breakdown or, at worst, very costly fires. Fire damage has also resulted from the gnawing of matches collected in the nest.
Disease Transmission
Historically, the role that rats and mice have played in the transmission of disease to humans has been of profound importance. The Black Death (Bubonic Plague), which claimed more than 25 million lives in 14th century Europe, is perhaps the most documented case history of rats and disease. The plague bacterium was transmitted from rat to rat (ship rats) and from rat to human by the oriental rat flea. The incidence of plague has not been entirely wiped out, but closer understanding of the mechanism involved has seen much reduction in the occurrence of this dreaded disease.
Among the many diseases transmitted to humans by rodents, perhaps the most insidious and widespread problem involves the distribution of food-poisoning organisms (eg. Salmonella bacteria). Unfortunately, the nature of disease organisms of this type is such that it will always be difficult to pinpoint, without any doubt, the cause of disease transmission. It is very likely that rats and mice play a significant role in the transmission of such diseases, particularly those which are gastro-intestinal and somewhat difficult to track back.
Rats and mice may transmit disease to humans by a variety of means:
• Contamination of food or utensils with rodent urine or faeces. Examples: Salmonella food poisoning (bacteria carried by rats and mice), chloriomeningitis, mild meningitis (virus carried by mice), Weil’s disease, infectious jaundice (bacteria), tapeworm.
• Contamination by direct contact with urine or faeces, where bacteria seem to enter the skin through small scratches; for example, Weil’s disease.
• Indirect contamination via blood-sucking insects (such as fleas); for example, bubonic plague, murine typhus fever (via fleas).
• Indirect contamination via pets to humans; for example, favus, skin disease (fungus from mice to pets to humans).
• Contamination by directly biting humans; for example, rat bite fever, relapsing fever (bacteria).
• Indirect contamination by being eaten by an indirect carrier; for example, trichinosis (worm infested rodent eaten by pig, worm infested pig eaten by human).
Rats and mice in buildings pose a serious threat to human health. The disease threat alone is justifiable cause for concern and for the implementation of sound control procedures.
PEST RODENTS
Norway Rat
(Also known as the common rat, sewer rat, brown rat and water rat).
The Norway Rat is the larger of the pest rats and has a thickset body, blunt snout, small close-set ears and a tail shorter than the length of its body. It normally lives 9-12 months and may have 5-6 litters per year (each with 8-10 young). The young achieve sexual maturity at 3-4 months. Clearly, its reproductive potential is very high.
The Norway Rat is very widespread in Melbourne, and is possibly the most economically detrimental pest rodent in Australia. It infests warehouses, factories, flour mills, poultry farms, garbage dumps, shops, supermarkets, domestic premises, grain storage facilities, sewers and many other locations that offer shelter and food. Outside buildings, these rats mostly live in burrows, which tunnel into stream banks, under buildings, under rubbish heaps and so on. Burrows commonly have ‘bolt holes’ hidden under debris or grass to facilitate fast emergency exits. They may enter buildings just for food, reside in buildings during the colder winter months, or live in buildings all year round. Nests in buildings are mostly located in wall voids, roof voids and other parts of the construction that offer a secretive, undisturbed area for shelter and access to food and water.
Norway Rats are typically omnivorous in their feeding habits and will eat all human and animal foods and feedstocks. They do need regular access to liquid water; so in conditions where their food is low in moisture and available water is minimal, liquid bait preparations may be effective.
Norway Rats are very much creatures of habit, and once they have explored a new environment, they establish quite rigid traveling routes. Being neophobic, they may take some days to adjust to new objects such as bait stations and traps.
In cases where the territory of Norway Rats overlaps that with other rodent species, it is entirely likely that the Norway Rat will become the dominant species, often driving others out of the area.
Roof Rat
(Also known as the black rat and ship rat)
The Roof Rat is the smaller of the pest rats and is of slighter build. It has a more pointed snout, large prominent ears and a longer tail than its body length. It normally lives 9-12 months and may have 4-5 litters per year (each with 6-8 young). The young achieve sexual maturity at 3-4 months.
The Roof Rat is often restricted to the indoors of premises and to areas around seaports. While Norway Rats are very suitable to rural life, where burrowing is advantageous, Roof Rats tend to be more restricted to city life, where their excellent climbing abilities avail them of numerous nesting sites often in the upper parts of tall buildings. This ability also facilitates their crossing from one building to another via connecting cables. Within buildings, Roof Rats are likely to nest in wall and roof voids, but they may range and feed freely all over the building. Outdoors they may nest among vines and trees, but they seldom burrow. They commonly infest ships.
Although Roof Rats are usually described as omnivorous, in practice they seem to consume a high proportion of vegetable and fruit material. Where they have ready access to foods with such a high moisture content, it is likely that they have a much reduced need for free water.
The Roof Rat can live in somewhat similar locations to those preferred by the Norway Rat; but if territories overlap, it is likely that the Roof Rat will be driven out.
House Mouse
(Also referred to as the field mouse)
The House Mouse is small and has rather large ears, a pointed snout and a tail at least as long as its body length. House mice living indoors are usually a darkish grey colour, with lighter grey on the belly, while those living mainly outdoors tend to a more sandy or yellow brown colouring ? hence the reference to ‘field mice’. They tend to live for about 1 year and may have 6-10 litters per year (each with 5-6 young). The young achieve sexual maturity at about 6 weeks.
The House Mouse may live indoors or outdoors, sometimes entering buildings only when climatic conditions are adverse. Being such small animals, their access into buildings is probably easier than is the case for rats and a greater range of nesting sites is available to them. Typically, within buildings they may nest in wall voids, cupboards, roof voids, stored foods, furniture and many other locations. Outdoors they live in burrows.
In their general behaviour, mice are much more curious and exploratory than rats, so trapping programs for mouse control can often be very effective. They are very good climbers, jumpers and swimmers, although they do not seem to swim very often.
In their feeding habits, mice are generally regarded as being quite omnivorous. A variety of foods (eg. nuts, grains, meat and animal feeds) may all be acceptable on baits or traps, depending on the main diet of the resident population. They are well adapted to low water intake and can live on just the moisture in grain without any supplementary intake of water. Preferably, though, they seem to enjoy dry cereals if free water is available. Mixing of certain baits with water can make them very attractive. Mice feed mostly around dusk and during the night, but if the area is relatively undisturbed, they may feed during the day as well. They seem to prefer to eat small amounts of food at various locations and at frequent intervals. Even though they do not directly consume large amounts of food, damage due to gnawing, nibbling and contamination with urine and faeces can be very widespread. In most cases, mice are not as suspicious of new food (baits) as rats.
In rural areas the occasional combination of mild weather, abundant food and shelter, and a reduction of natural enemies may cause mice to multiply to plague proportions, and then to migrate. Massive migrations can cause very significant damage and losses to farms and other buildings.
Rodent Control Methods
Pest control operators called to control rodents infesting a building may choose to use one method, or a combination of methods, depending on the circumstances.
Procedures may include the following:
Sanitation – reducing the food and shelter available for rodent activity.
Rodent-proofing – altering the building structurally so that rodents cannot gain entry.
Trapping – using traps to capture rodents.
Chemical control – baiting with multiple or single dose anticoagulant rodenticides.
The control of some high-health risk, large scale rodent infestations may require the implementation of several of the procedures outlined above. In dealing with all rodent problems, however, irrespective of the type of control treatment undertaken, the observant operator will always look for signs of poor sanitation and hygiene practices that, unless corrected, will continue to invite these unwelcome visitors.
Non-chemical control
Sanitation
It is quite reasonable to suppose that decreasing the food and shelter available to a given population of rodents is likely to lead to more competition between individuals and, eventually, to a decline in the number of rodent present. This aspect of rodent control often involves a largely educational component, whereby the pest control operator, following a thorough inspection of the premises, may advise the client about hygiene and sanitation in relation to rodent infestation. The operator may advise the use of sound garbage containers with tight fitting lids, a clean-up of rubbish heaps and overgrown weeds around the building, or cleaning of the building immediately after the day’s work is completed, rather than on the following morning.
Each situation will be different, so each should be carefully inspected and assessed and then sound advice given. The operator, while inspecting and questioning, will be constantly looking for conditions of food and shelter that may help to sustain a rodent population. The importance of achieving and maintaining a high standard of hygiene and sanitation, in relation to the control or prevention of rodent infestation, cannot be overemphasized.
Rodent-proofing
Perhaps the most permanent method of rodent control is to make alterations to the building so as to prevent their entry. It is again necessary to carry out a thorough inspection of the premises, locating all cracks, crevices, holes and other potential access points that could allow the entry of rodents. All possible entry points should be blocked, using only sturdy, durable materials such as cast iron grills, heavy-gauge sheet metal, and rich cement mortar or concrete mixes. Materials such as plastics, wood and softer metals (eg lead) should be avoided, as rodents can gnaw through these.
Trapping
Trapping is a technique of rodent control that is not as popular in present day pest control as it was in the past. This is probably because trapping can demand much time, skill and labour, and the variety of chemical control methods now available are often seen as more cost-effective. There are still, however, situations where trapping is a more appropriate method.
Trapping can be useful:
• For rodent control in premises where inaccessible dead rats cannot be tolerated.
• For rodent control in premises where chemical pesticides are not tolerated.
• For cleaning up remaining ‘bait-shy’ individuals after a baiting program.
Chemical Control
Owing to the widespread use of the safer anticoagulant rodenticides, the traditional single-dose poisons have been experiencing a significant decline in use. This decline is largely attributable to their often highly toxic nature, whereby one accidental feeding by a non-target animal is very likely to cause death. There may, however, be circumstances in which these single dose poisons are still useful, for example, where a quick knockdown of a rodent population is required owing to a significant disease risk, or in circumstances where anticoagulant baits are not sufficiently effective. When a rodent control program is to include the use of single dose poisons, it is essential that the work be carried out by qualified operators with appropriate permits/permission.
Pre-Baiting
Rats mostly use the same routes when traveling and tend to know their immediate environment very well. Unlike mice, their behaviour shows an aversion to new objects in their environment, so it may take a few days before the more suspicious rat will try a new food in a container, while the more adventurous mouse may begin to investigate within minutes.
In this situation for bait-shy rats, before prepared baits are laid down, it is usually advisable to pre-bait. This involves laying down attractive food as the bait, except for the poison. This may be carried out for a few successive sessions, or perhaps until the rodents appear to be feeding freely. Once their feeding habit has been established, the bait should be altered to contain the poison. This procedure lessens the likelihood of creating bait-shyness in rats.
Baiting
A variety of foods are used in the preparation of poison baits, including bread, cereals, fish, meat, prawns, fruits, nuts, seeds or vegetables. The choice of food will take into account the feeding habits of the rodents to be controlled and, owing to the toxicity of the baits, they should be placed so that they are inaccessible to pets, children and other non-target animals. The introduction of lockable bait traps has lessened the chance of this occurring. Due to the nature of rats and mice feeding habits, situating the bait in an enclosed or sheltered area is recommended to give the rodent coverage and protection while feeding, and to place it in the rodents’ runway or near burrows or harbourages.
Baits should be removed when no longer required, as they may facilitate the breeding of various beetles.