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Rats (Rattus Norvegicus)

Environmental Health

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Rats

Rats are one of the most commonly complained of pests in our society. They are well adapted to living in harmony with man in his own environment. 

Rats are more often found outdoors and in sewers.  They are good burrowers, agile climbers, and excellent swimmers.  They spread various diseases such as Salmonella and Weils disease, which can be fatal to man. 

They cause structural damage to premises and sewers by their burrowing, as well as their constant gnawing on wood, cables, pipes and household items.  Unlike mice, rats need water everyday.


Habits and habitat

Burrows and can live outdoors, indoors and in sewers.  They are very good swimmers.  Often follow the same tracks.  They avoid unfamiliar objects placed in their territory for some days.  Range 50 – 100 meters.

Rats have an excellent sense of smell and hearing.  Their sight is very poor.  They are colour blind  and can only make out shapes.

 

Feeding habits

Rats will eat all types of food. They consume 30 – 50 grams per day.

 

Life cycle

The life expectancy of rats is around one year. A female will typically breed five times with an average litter of seven or eight.  Breeding occurs throughout the year but especially in the spring and autumn.

 

Evidence to look for

  • Fresh droppings will be soft and moist.  They will usually be brown to black.    They are capsule shaped and about 20mm long.  Rats leave about 50 droppings a day.  Diseases are spread through droppings and urine. You could find them under your kitchen sink, in the hot press, in your loft, and your garage.

  • Fresh gnawing of wood, carpets, papers, cables, household items, furniture, etc.

  • Holes.  Rats will burrow under sheds, paving stones, etc.  The hole will be 50-80mm in diameter and shallow, with dirt usually piled up outside it 

  • Damage to foodstuffs and household items in cupboards and lofts.

  • Smear marks - rat hair is oily and leaves a dark stain around well-used entry points.

  • Runs, tracks, pads.  Constant use of the same tracks in grass and soil will result in a "trail" of matted grass or trodden soil being made on the ground.

  • Live or dead rats.

  • A bad smell.

 

How to prevent rats

  • Rats only need a gap of 25mm to gain entry.  (The size of a ten pence)  Ensure that all gaps around external drainpipes, door and window frames, etc are filled in.

  • Ventilation bricks and slots should already have a fine wire mesh incorporated in them.  If this has worn away, replace it externally with a fine insect mesh.

  • Gaps around heating and water pipes indoors and outdoors should be sealed with particular attention given to water pipes from boilers.

  • Regular inspection of the manhole should be made to ensure that they are free from rats.

  • Self-closing door mechanisms should be fitted to back doors to ensure these remain closed as rats can enter premises through open doors.

  • Make sure that all food stuffs and supplies of water are covered. 

  • In the garden grass should be cut regularly and all weeds removed. As these provide food and shelter for rats.  Garden sheds, etc. should be kept at least 25cm off the ground.

  • Don't leave rubbish lying around the house or garden.  Put it in the bin!

  • All garden tools and toys should be stacked neatly when not in use.

  • Bins should be kept closed at all times. 

  • Feeding birds can attract rats. If there are rats about  use bird feeders rather than scattering food on the ground.

 

Treatment

There are various ways to treat the problem yourself, using bait and traps.

 

Bait

This is the quickest way to control rats in your property, but could result in a bad smell. Make sure you follow all instructions on the package.

  • Ensure that children and domestic animals do not have access to the bait.

  • Where possible, try and put bait into holes, in lofts, and along rat runs.  Because of their fear of new objects, rats will not eat bait for the first 2-3 days.

  • Inspect bait regularly.  Continue to top up bait until no more is eaten.

  • Remove all bait when problem is cleared.

  • Most bait will take between 4-12 days to kill rats.  It will not kill them overnight!

 

Traps

  • Most adult rats know what traps and cages are and how to get the bait out of them without getting caught.

  • If using traps or cages, ensure that they are placed along rat runs and away from children and non target animals.  Use a cereal-based biscuit for bait.  Remove dead rats from traps and always reuse the trap.  Rats like the smell of their own kind and will be more inclined to go into traps that have been used.  Dispose humanely of rats caught in cages.  Drowning is not recommended.

  • Sticky glues are inhumane and we do not recommend them

If  you feel that you cannot carry out this work yourself, the Pest Control Officer can do it for you.  There may be a charge for this service.