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RODENT CONTROL
There are only two kinds of rat in this country, the brown or common
rat and the ship or black rat. The first, as its name implies, is much the
commoner in most districts and is the only rat found in Hornsey. Coming
from treeless plains, it is a burrowing animal which feeds on roots, growing
crops and any animal it can kill. It also feeds on any garbage or offal
available, doing considerable damage. The rats feed chiefly at night at
any place where food is left exposed and accessible; they always try to
feed under cover.
The extent of the problem of eradication can be judged from the fact
that rats breed from the age of six months onwards and produce four or
five litters in a year, each of from four to ten young; even larger litters
have been recorded. A litter of twenty-three young rats with tie parent
rats has been removed from a nest in this borough. Fortunately there is
a high mortality among young rats.
The urgent need for every effort in extermination is emphasized by
their ability to spoil and waste food of all kinds and their wholesale
destruction of property.
As rats will eat almost anything, even the sick and young of their own
kind, it is virtually impossible to starve them out and fecundity assures
their survival even if as many as 90 per cent of them are killed at one time.
The underlying principle of modern rodent control is to kill off all the
rats and mice within the infested area in as short a time as possible, and
may consist of poisoning, gassing, or trapping.
It has been estimated that, given ideal breeding conditions, a pair of
rats can be responsible in the course of a year for as many as 600 progeny,
but very few are likely to survive, the others falling victims to disease,
attack by other rats and the activities of rodent operators.
In every case of infestation by rats and mice, systematic treatment is
carried out by using the methods recommended by the Ministry of
Agriculture and Fisheries (Infestation Control Division). One rodent
operator is employed on this important work under the general supervision
of the sanitary inspectors.
A careful survey is made in each case to determine the extent of the
infestation, the location of runs, living quarters and feeding grounds in
order to decide the best baiting points and type of bait to be used having
regard to necessary safety precautions. Finally, occupiers are advised as
to hygiene and rat proofing of the premises.
All baits must be finely divided so that they cannot be carried away and
stored by rats and the various bait bases used are sausage rusk, bread
rusk, wheat and oatmeal, and various poisons such as zinc phosphide,
barium carbonate, arsenic, red squill, a blood coagulant known as
"warfarin", and cyanide gas.
There are various methods of baiting, the real object of which is to gain
the confidence of the rat and overcome that caution so characteristic of its
behaviour. This is generally attained on the fourth day when rats are
feeding freely and without fear. On the fifth day poison bait is laid.
Regular treatment of sewers is an important contribution in the prevention
of surface infestation.
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