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11
RAT REPRESSION.
Your Rodent Officer, Mr. Carter, has submitted the following report on the progress of rat
repression within the boundaries of the City during the year.
The work has been carried out under the Rats and Mice (Destruction) Act, 1919. and in compliance
with the general "Direction" issued to all Local Authorities by the Minister of Food, in exercise
of his powers by virtue of the Infestation Order, S.R. & 0.680, 1943. These powers have since been
transferred to the Ministry of Agriculture and Fisheries.
The department engaged on this work comprised the Rodent Officer and six assistants or
operators.
It has not been necessary to serve Statutory Notices under the Act, as occupiers of property have
readily co-operated, it being generally realised that the primary factor in achieving the maximum
results in work of this nature, was the co-ordination and application of the measures taken by
operators, whose sole concern is the destruction of rats and mice.
The work was divided under three headings, inspections of blocks of properties to ascertain the
presence of rats and mice, surface treatment of premises found to be infested, and periodical maintenance
treatment of sewers.
A total of 3,194 premises were inspected during the period under review, embracing all types
of properties, from riverside wharves and warehouses, blocks of offices, factories, kitchens, workshops,
to domestic dwellings.
Pre-baiting and poisoning have been the principle means of extermination with trapping as a
secondary measure, and in all instances the measures advised by the Infestation Branch of the
Ministry have been adhered to.
The character of infestations remains fairly constant, in a ratio of 9: 1 Ship (Black) rat and
Common (Brown) rat respectively.
Altogether, 705 infestations of rats, and/or mice were treated and this entailed 8,759 re-visits for
operational purposes.
In the process of pre-baiting, 18,226 initial points were selected, and 88,980 pre-baits were put
down. Approximately 11 cwts. of poison bait, spread over 11,123 poison points, was used in surface
properties.
These measures resulted in an estimated kill of 7,269 rats and of this number 2,183 bodies or
30 per cent. were picked up. Trapping was the means of destroying 484 rats, and added to those
found after poisoning, gives a total of 2,667 bodies taken from premises.
As explained in previous reports, the estimated figure is a minimum and could possibly be
increased by 30 per cent. It is relatively unimportant, but at the same time useful for record purposes.
The best test of the results of a treatment is the freedom of the property from live rats, at least for a,
reasonable time.
As agreed with the Ministry of Agriculture and Fisheries, two sewer maintenance treatments
were applied in May and December.
The May treatment resulted in an estimated kill of 502 rats, and the December treatment 725
rats, of which 47 bodies were found on the benches of the sewers.
Assessing the value of this work, the effect on surface infestations of Common rat must be
considered, as there is always a possibility of a connection, and it is reasonable to assume that the
small number of Common rat infestations found in premises is in some measure attributable to these
treatments.
Unfortunately this work does not affect the Ship (Black) rat, which lives and breeds solely
above ground.
A considerable number of mice infestations were treated and satisfactory results were obtained.
Altogether 330 bodies were found after poisoning and trapping. There has been an increase in this
type of infestation. This appears to be due to the carcless disposal of food scraps and wrappers,
usually deposited in waste-paper baskets in offices, and thrown on the floors in factories, etc. Pre-war
most business premises were cleaned at night, but now this is mainly carried out in the early morning,
so that waste food, orange peel, sweet wrappers, &c., are left all night to attract rats and mice, and
provide the neccssary sustenance. In such cases the provision of small metal bins is advised.
The value of preventive measures is realised, and where practicable, structural and incidental
rat proofing is advised and combined with extermination measures. Unfortunately, many premises
treated were beyond structural proofing against Ship rat, or alternately it entailed work which could
not be undertaken at the present time. Many of the older properties have lost their original identity
owing to internal alterations and additions over a number of years, and such alterations have in
many cases provided excellent harbourage and runs through the structures from one building to
another, a facility of which the ship rat is quick to take advantage.
It is understood that the Minister of Agriculture and Fisheries contemplates frosh legislation
in the near future to supersede the present Act, in the light of knowledge and experience gained and
conditions existing to-day. As far as the City conditions are concerned, an exceliont opportunity is
provided for including in any such legislation the compulsory rat proofing of all properties to bo
erectcd in the future. This would entail close co-operation between architects, builders, and competent
officials of Local Authorities in every case.
Such proofing would include the elimination of external pipe services providing runs, or, if used,
the provision of "rat guards" at roof gutter level, and between the lowest external window and ground
level. Where possible, internal pipe services should not be eased, and in every instance sealed off at
floor and ceiling levels. False ceilings, floors, and panelled walls should be avoided. Water storage
tanks and automatic flushing cisterns must always be covered, and enclosed raised inspection platforms
avoided. All doors providing entry to the building at roof level, should be rat proofed and selfclosing.
Ventilation louvres in lavatories should be avoided and wire mesh substituted. These items
are by no means exhaustive, but lack of attention to such details has in the past been responsible for
infestations in many cases.