Rodents are a particular type of mammals. Those about six inches long are called rats. Many rodents are larger than rats like porcupine and some smaller called mice. Rats, the most abundant mammal pests are colour-blind and find their food and mates through smell.

Rats cause loss to crops, stored grains, electric wires in homes and factories, canal bunds and other things. They damage sugarcane, rice, groundnuts and wheat. Besides, consuming grain, they deteriorate the quality of wheat with their faeces, urine and hairs. In Pakistan, there are many kinds of rats but those mentioned below are dangerous for agriculture.

There are four kinds of field rats: Indian rat is relatively big and weigh about 400 grams and is found in lower Sindh, Northern Punjab and humid areas of the frontier province. It is dark grey with thick hair and can burrow a one and half meter deep hole in soil. This rat damages rice, maize and sugarcane crops but is rarely found in buildings in contrast to India where it is a major urban pest.

This rat stores a huge quantity of grain in burrow and the stock can last for two to three months after harvesting of crop. It breeds throughout the years but faster at crop maturity time. Being a nocturnal rat, it searches food during night time.

The second type is soft furred rat which is found in the humid area of Sindh and Punjab. It remains concealed in big mounds of mud after wheat and rice harvest. It is relatively smaller than Indian breed, blind and of grey colour with soft skin and white abdomen and big eyes and ears. Its diet is different from others as it consumes a mixed diet of seeds, worms and insects. It keeps feeding on sugarcane even after harvesting of crop. It is a serious pest on sugarcane, wheat and rice.

The third kind is small tailed rat found throughout the country where soil is damp and hard packed. Its presence is indicated by mounds of loose soil, along watercourses bunds. It inflicts considerable damage to wheat, rice, sugarcane, oilseed crops and forest nurseries. This rat cuts roots of nursery trees, eats sugarcane from underground and damages root crops.

During rice and wheat harvest, it feeds on surface and damages the crop. It also causes breaches in canals and distributaries. It remains most of the time in soil but comes out for food.

The fourth, sandy soil rat lives in sandy areas and has long black hair on its tail. It damages groundnuts, wheat and gram.

Household and godown rats are of three types. The first is the household rat or rattus rattus found throughout Pakistan. By mostly remaining in houses and godowns, it feeds on stored grain and food leftovers in houses.

It is a major pest in grain stores, food stores, poultry farm, and industrial premises and is agile to climb trees. It is grain or seed eater but inflicts heavy damage to coconut plantation, living and nesting in the crown of palm tress. It also feeds on eggs in poultry laying sheds and sometimes gnaws the insulation off electric wires or plastic piping. It has a long tail, usually one and one quarter times as long as their bodies. It can breed in every month but mostly in warm months from spring up to autumn.

The second breed is brown/Norway or rattus norvegicus also known as sewer or common rat in Europe and North America. In Pakistan, it is confined mainly to Karachi city with small population in coastal towns of Pasni and Gwadar with a small population in and around Lahore railway station and sidings. It is found in godowns, harbours, houses and mostly remains concealed in drain and garbage. It is heavy-bodied with broad blunt muzzles and small naked ears.

The third type is house mouse or mus musculus found throughout the country. Its ears are large and naked and the muzzle slender and tapered to a point. As it is extremely agile, it can climb up rough walls and between crevices, finding way into buildings and even closed cupboards and boxes. It damages crops and grains in godowns.

For controlling the menace, the identification of rat, loss estimation, easy and cheap controlling method and its numbers are necessary. The oldest and safe method is trapping the rodent. It is successful in a limited area and satisfies the farmer or the wares-house keeper. This method has several advantages as it enables to identify the species and the rat density.

Another method is through pesticides in which three types of pesticides are used for killing rats. These are acute poison, chronic poison and fumigants which are quick acting and slow acting poisons, respectively.

Scientists of vertebrate pest control institute (PARC) have developed rat bait known as PARC Rat bait. Tasty ingredients are added to it which attracts the rat. The field infested with rats should be baited right after sowing of the crop. Baiting should be stopped two weeks before the harvesting of crop.

There are tablets like phostoxin or Detia produce a gas called phosphine used for controlling insects and rats. These tablets are always used in closed and airtight spaces. Cymag powder may also be used for the purpose. This powder produces a gas after mixing with moisture. The powder is inserted into burrows with the help of spoon tied on a long stick. After putting powder, holes should be tightly closed.