Truly Nolen India

Rodents: Rats and Mice

The Rodents are a large group of mammals with over 1500 representative species worldwide. This is close to 40% of mammals consist of one group of Rodents.

Rats have lived in close association with man ever since dawn of civilization when he gave up nomadic life and settled down to farming with a roof over his head. In spite of living close to man and sharing his food and abode, rats have always remained undomesticated.

Rodents are most easily distinguished from other mammals by the characteristic arrangement and form of their teeth. They have only a single pair of incisors in both upper and lower jaws and no canines. The wide gap (diastema) between the paired incisors and the molars gives the rodent skull an unmistakable appearance.

The incisors form the clue to the tremendous success of rodents with in the animal kingdom. Rodent incisors have three basic characteristics that together distinguish them from the teeth of most other animals; they are strongly curved, they grow continuously throughout the animal’s life, and they carry a thick layer of enamel on the outer side only.

The fact that rodents’ incisors grow continuously means they must also be worn away continuously. It is often said that rodents must gnaw in order to prevent their excessive growth, but this is not necessarily true, rodents can wear away their incisors by rubbing the lower set against the upper set. This results in softer dentine wearing more rapidly than the hard enamel, giving a chisel like outer edge to the teeth. In the gnawing of rats and mice they can penetrate soft metals such as lead and aluminum.

Rats and mice are now present throughout the world. Their adaptability has enabled them to survive extremes of climate from the frozen tundra to dry arid deserts. They were amongst the first animals to be fired from the earth in rockets. They also played a major role in the development of modern medicine.

Rats and mice are collectively called as commensal rodents. The word commensal means “sharing one’s table. Rats and mice have been sharing people’s food and shelter for many years. The word rodent means “to gnaw.” Like all rodents, rats and mice possess chisel like incisor teeth which grow continuously through out their lives. These incisors are kept filed and sharp primarily by the rodents grinding the incisors against one another, and secondarily by the rodents constantly gnawing the on various objects.

There are three species of commensal rodents which are of most concerned with the pest control professional.

Types of Distribution

In India There are about 136 species of rodents are recorded, However very few about 15 to 16 species are of economic importance. These can be divided into 4 broad groups, based on their relationship with man.

Transmission of Diseases

The diseases transmitted by rodents and other animals to men are known as Zoonoses and there is a wide range on a world wide basis.


Leptospirosis or Weils Disease


Murine Typhus Fever

Rodents as economic pests

Commensal rodents

House mouse: Mus musculus

House mouse is identified by a small slender body weighing around 15 to 25 grams as an adult. Ears are large; tail is semi naked and is as long as the head and the body together, dark grey in colour.

Biology and reproduction

When the living conditions are very good (plenty of food, water and shelter) rodents can multiply. The female produces

Bandicoot rats: Bandicota bengalensis

Bandicoots are known as field rats and have stocky body, are larger, stronger, more aggressive. This rodent is also found in fields and cause enormous damage. They have burrowing habit. In urban areas this rodent is often found near garbage dumps, railway tracks, outside buildings and apartments. Their presence is confirmed by presence of burrows around the buildings.

Roof rat: Rattus rattus

The roof rat is also known as the black rat, ship rat. The roof rat is appropriately named because by nature it is good climber and commonly lives above the ground in “roof” or aerial areas around structures. Their nests may be located in trees, clinging vines or on the sides of buildings and fences or inside buildings in attic area, ceiling voids. Roof rats enter buildings from the roof or by using various utility lines. If population builds up they expand their nesting areas to include underground burrows within industrial and residential landscape areas, ground floor areas inside buildings, under pile of rubbish.

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