| The two major pest species of rat are the Norway Rat (often referred to as the common rat, sewer rat, brown rat and water rat) and the Roof Rat (often referred to as the black rat or ship rat). They are both common in the main population centers of Australia and most countries throughout the world. Since early times rodents (rats in particular) have been responsible for the loss and contamination of feed from crop stage through to the storage of processed food in both residential and commercial premises. Rodents have been associated with the transmission of disease organisms, the most notable being the occurrence of the Bubonic Plague in Europe, causing the loss of 25 million lives. |
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Where they live and what they eat?
As climatic conditions become less favorable during the onset of winter months, rodents tend to move indoors looking for both food and shelter, however in commercial premises rodents can be a problem all year round. They construct their nests utilizing soft materials, such as shredded paper or fabrics, close to where they scavenge for food and water. Rodents actively forage for food at night and are seldom seen during the day. Their diet includes food material of both animal and plant origin and they also require access to water, unlike the House Mouse that can obtains sufficient water from foods that it digests.
Why they are considered pests?
Before examining each of these rat species in close detail there are some general characteristics to be considered.
Contamination:
As rats move in and around foodstuffs, 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.
Gnawing:
The constant gnawing of rats can be the cause of serious damage to a range of materials. Rats have large front teeth called incisors that continually grow, and it is essential they gnaw at frequent intervals to ensure their teeth are kept short, to enable them to feed and fight.
Sense:
The senses of rats are mostly very keen with the exception of sight. Their eyes are poorly developed giving them dull and blurry vision. They have an acute sense of taste and smell enabling then to detect strange elements in food which can lead to ‘bait shyness’ in baiting programs. They also have very keen touch and hearing senses. Rats are known to be Neophobic (fear of new objects) and this can cause them to shy away from traps and bait stations when they are first installed, often taking a few days to ‘warm’ up to them.
How to get rid of Rats
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A single pair of mating rats can produce a rodent population of 400 –700 within a year; because of this it is very important that preventative and control measures are undertaken.
The most permanent method of rodent control is proofing, this involves making alterations to a building so as to prevent their entry. Thorough inspection of the entire building is required to locate all possible entry points including, gaps around plumbing and under doors. These entry points should then be blocked and sealed using only durable materials such as, sheet metal, bricks and concrete. Materials such as plastics wood and softer metals (eg. lead) should be avoided as rats can gnaw through these.
Another sound control method is, implementing good sanitation and hygiene practices. Eliminating rubbish and built up waste materials around buildings and by using tight fitting lids on external bins and refuse containers, can greatly reduce the risk of infestation.
For trapping and baiting of current or future infestations, a professional pest controller should be sought.
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Types of Rats
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Norway Rat (Rattus norvegicus)
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 its body length. 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.
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Roof Rat (Rattus rattus)
The Roof Rat is smaller than the Norway Rat and is of slighter build. It has a more pointed snout, large prominent ears and a tail longer than it 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.
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