Common name

Scientific name

What it does

Rice field rats cut or pull up transplanted plants. They also chop young seedlings. At ripening stage, they feed on developing rice buds.

Why and where it occurs

In lowland irrigated rice crops both the wet and dry seasons are favourable for rat reproduction and crop damage. In rainfed rice crops rodents have their greatest impact in the wet season. The availability of food, water, and shelter are factors, which provide optimum breeding conditions. The presence of grassy weeds also triggers their development.

Rice field rats feed at night with high activity at dusk and dawn. At daytime, they are found among vegetation, weeds, or maturing fields. During fallow period, they utilize major channels and village gardens as prime habitats. At tillering, 75% of time they are in burrows along the banks and after maximum tillering, 65% of time they are in rice paddies.

How to identify

Rat feeding can cause the following damages:

• Missing germinating seeds
• Missing hills
• Chopped young seedlings
• Missing plants
• Irregular cuttings of stem
• Chewed developing buds or ripening grains
• Tillers cut near base at 45° angle
• Retillering of stems
• Delayed grain maturity
• Missing grains
• Missing panicles

The feeding damage on the stem caused by the rice field rats may resemble insect damage although rat damage is usually distinguished by the clean cut at 45° of the tiller. The damage on the grains is similar to bird damage.

• Check muddy areas for runways, active burrows, and footprints of rice field rats. These are usually near the damage they have created.
• Check for presence of rice field rats: cut tillers and active holes on the bunds that surround the fields.
• When possible, catch rats to identify the species. Place traps along runways, or dug the rats from their burrows.

Click on images to enlarge

Adult rice field rat

How to manage

Early action is most effective. Particularly, management measures should be done when rats are not breeding.

Community rat control

Before planting is the best time to organize community rat control campaigns. These community rat control can be done until three weeks after planting.

• Flooding, digging, or fumagating rat burrows
• Scare rats out of areas with high vegetation cover or around villages (using netting, dogs, clubs, and others to catch rats)
• Use dogs to locate active rat burrows, then do Step 1
• Hunt rats at night using flashlights, clubs, bow and arrows, and netting
• Set local kill-traps along runways of rats
• Use registered rat poisons that are placed in covered bait stations (but not where children, pets, or livestock have easy access).

Management actions

• Keep rice bunds (banks) in the crops less than 30 cm wide to prevent rats from burrowing.
• Keep the edges of the field, the bunds, and surrounding areas clean and free of tall weeds and hiding areas for rats.
• Plant at the same time as your neighbors—within 2 weeks of each other.
• Strategic use of Trap Barrier System (TBS)—during the rice season with the most rodent damage.
• Keep area around fields, homes, and villages clean — no piles of wood or brush, no garbage heaps, no weedy areas.
• Keep grain stores and surrounding area clean.

Learn more

View full fact sheet:
Rats on IRRI Rice Knowledge Bank