Advice to Householders - Rats & Mice
Mouse:- Brownish grey in colour, the body is
80-100mm long, the tail is 80-100 mm long, it weighs between 14
& 20gms, has a slender and small build, has a pointed nose,
large hairy ears and pink feet. The droppings are small spindle
shaped or irregular.
Rat:- Brownish grey with grey belly fur, 200-270mm
in length with the tail 165-205 mm in length, weighs between 200
& 500gms, has a large and thickset build, a blunt nose, short
thick opaque finely haired ears, and grey feet. The droppings are
banana or sausage shaped
Ship Rat:- this can be grey, black,
brown or tawny and may have white belly fur, its body is 145-200mm
in length and its tail is 250mm long, it has a slender and
streamlined build, a pointed nose, its ears are large, thin,
translucent and almost hairless with pink feet. The droppings are
ellipsoid or spindle shaped.
Rats are intelligent and social animals. They live in
colonies, which may be several hundred strong and can jump, swim,
climb and prefer to move under the cover of darkness. They have a
strong tendency to burrow, especially into soil or under secure
coverings such as piles of rocks. They are frequently found living
near water, by drains, along ditches, streams and sewers.
Occasionally they live inside buildings in spaces between walls, in
lofts or beneath piles of rubbish. Due to their agility they can
squeeze through small openings and it is very difficult to keep
Their wide-ranging habitat means that they are never far away
from human activities and will infest anywhere that has a suitable
food supply for them. An infestation can build up rapidly without
you knowing about it as they are more active at night. If you do
see a rat during the day then there is a sizeable colony
Rats establish runways which are regularly used to travel from
their nest to a food and water supply which give rise to signs as
to where to bait by finding droppings, grease smears, footprints
and signs of gnawing. But they do not like new things and as a
result may not take from the bait stations straight away, they need
to get used to something new being there.
Mice, on the other hand are inquisitive creatures and
lots of small bait stations will attract their attention providing
it tastes good. Mice can be more of a problem than rats
as they do live indoors, they are therefore likely to cause more
damage to food stuffs and cabling through their constant gnawing.
They also can get through very
small gaps and build their nests in areas that are
difficult to get to.
Signs of Infestations
Often the first sign of rodents is finding droppings. Rat
droppings are approximately 1cm long and rod shaped, whilst mice
droppings are similar in size to a grain of rice. Other
evidence include footprints in dust, gnawing of packages and
furniture, nesting sites, smear marks.
Rats and mice carry diseases including salmonella,
Leptospirosis, Weil's disease, Murine typhus, Viruses, parasites,
Brucellosis, Aujeszky's disease and foot & mouth disease.
Whilst disease transmission to man from rats is a potential
problem, it is a greater risk in farm animals. Rats are a major
hazard to livestock production especially pigs, calves and poultry.
Control must be a top priority.
A healthy female can produce up to five litters a year each of
8-10 young. Gestation is 21 days and offspring can reach maturity
in 8-12 weeks. As many as 30% of the females in a colony can be
pregnant at any one time.
Mice follow a very similar pattern except that they reach
sexual maturity after only 42 days thus can increase the size of
their colony much quicker than the rat.
Methods of Control
a) Trapping - it is best to
use a large number of traps for a more successful treatment.
Place traps in the area of the infestation, at an angle.
Suggested bait to be placed on traps are small pieces of fruit e.g.
strawberry, chocolate, peanut butter, or cereal.
b) Rodenticides;- The only effective
way to deal with an infestation in the first place is by using
these to kill off the population. Different types of bait are
available and they have differing degrees of success on each of the
When treating mice lots of small bait feeding stations are
necessary as mice are curious and move from food source to food
source. However if the bait is not palatable to them, or they have
access to a better food source then they will become 'bait shy' and
not take the bait, which obviously leads to greater problems.
Rats on the other hand have to get used to anything new and
will not feed from a bait station until they have got used to it
being it there. Therefore it does take a little bit longer to start
treating a rat infestation with the use of bait. It is therefore
essential that once again any alternative food source is
Lack of success in controlling an infestation is usually down
to poor application of the baits. Once this has been corrected if
there are still not takes form the bait then bait resistance must
be considered and further advice sought from MAFF (Ministry of
Agriculture, Fisheries and Food).
TAKE CARE WHEN PLACING ANY POISON OR TRAPS.
ALWAYS LAY THE POISON IN A SAFE POSITION. FOLLOW
MANUFACTURERS INSTRUCTIONS AND ENSURE CHILDREN AND ANIMALS CANNOT
GET ACCESS TO THE POISON OR TRAPS.
c) Hygiene/management:- It is essential
that basic housekeeping is good. All food sources should be removed
and refuse kept in covered containers, preferably rodent proof
ones. Sources of water such as dripping taps and leaky pipes must
also be removed. Proofing of the building is essential to prevent
rodents re-entering the premises . Blocking up holes where service
pipes enter the premises, any holes behind kitchen cupboards,
ensuring no gaps between floors and floorboards ensure that doors
fit properly or have bristle strips fitted to them or steel plates
etc. Air vents should be covered with a metal mesh, which will
prevent rodents getting in but still allow air through. Ensure that
any holes under the eaves etc are filled. Any drain breaks also
need to be repaired to prevent rats from the sewers getting into
your private drains.
Any holes that may allow rats or mice to gain entry to the
property should be sealed up.
Poisoned rodents will usually attempt to return to their nesting
area to die. If this happens, a smell may occur, which can
last a few days. The small can be masked with air fresheners
or rodent deodorant.
Please be advised that we are not responsible for any injury or
damage caused where persons carry out treatment themselves.
Ensure you follow the manufacturers instructions carefully when
using any product. Keep any insecticide or rodenticide away
from children and animals and ensure it is stored safely.
If you require any further information contact Environmental