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inspection to be infested, recommendation and supervision of structural and incidental proofing,
and periodical maintenance control measures for the destruction of Common rats in the City
sewers.
No difficulty has arisen necessitating statutory action to resolve the problem, and the continued
policy of seeking the co-operation of owners and occupiers has again proved most
satisfactory.
A major proportion of the work comprised inspection of defined areas for the purpose of
instituting collective action. In instances of individual notification of infestation, or request for
assistance in control measures, the remaining occupancies and adjoining properties were inspected,
and where necessary combined action taken.
A total of 3,743 occupancies and properties were the subject of inspection, such properties
ranging from new developments in varying stages of construction, until finally occupied, riverside
food warehouses and adjoining premises, food markets, public and private catering establishments,
blocks of offices, shops and factories, to domestic dwellings.
Altogether 592 complaints were received either by notification or as the result of inspection,
and of this total 531 infestations were the subject of control measures. In 61 instances no action
other than advice was found necessary. These were mainly instances where an odd stray mouse
had been seen by an officer cleaner during late evening or early morning, but the often long
procedure of investigation to ascertain if it was merely an isolated case or the distribution
fringe of an infestation elsewhere in the premises still had to be applied. Such notifications do,
however, indicate the increasing awareness of employers and employees of even very minor
nuisances and their readiness to seek advice and assistance. From the rodent control aspect
this is an attitude to be encouraged, as from past experience many infestations of both rats and
mice, some approaching major degree, have been traced as the result of a complaint of a minor or
even frivolous nature, and in some instances by an innocuous remark during routine inspection.
Continued routine inspection has fostered this attitude, encouraged the public, and strengthened
their co-operation.
The total of 531 infestations subject of treatment comprised 2 major and 74 minor infestations
of rats, and 14 major and 441 minor infestations of mice. Of the rat infestations, 2 major
and 49 minor were of Common (Brown) rat character and the remaining 25 minor infestations came
under the Ship (Black) rat classification.
Treatment of these surface infestations entailed 4,665 visits for operational purposes, and
in the process of control measures for rats, 1,447 initial baiting points were selected, 5,539
prebaits and 506 poison baits were laid. This resulted in a minimum estimated kill of 555 rats
and of this number .283 bodies were removed from the various premises or sites. The use of
Warfarin anti-coagulant rodenticides for the control of mice entailed the application of 9,495
initial baiting points, and 897 bodies were recovered.
In 1947, for example, the comparable figures were 643 rat infestations treated, 313 major
(20-200 rats) and 330 minor infestations, and control measures resulted in a minimum estimated
kill of 6,969 rats, of which 2,535 bodies were recovered.
In 36 instances structural ratproofing was carried out by owners or occupiers and in 30 cases
defective drainage resulting in Common rat infestation was remedied. Incidental rat and mouse
proofing in the nature of removal of harbourage provided by unnecessary and undisturbed accumulations
has again received unremitting attention, and the assistance and co-operation of The
Director of Public Cleansing and his Inspectors in this respect has been invaluable.
The low level of Ship (Black) rat infestation achieved in recent years has been maintained,
and the number of infestations of this nature (25 minor) was again exceeded by that of Common
(Brown) rat (51). In the year 1947 already mentioned, when 643 infestations were treated, 595
infestations were Ship rat and 48 Common rat.
To illustrate further the decline in rat infestation the up to date summary collated from
detailed information kept since 1944, is included as a useful record. It should, however, be
understood that the figures referring to rat infestation is the combined total of Ship and Common
rat infestation, the former comprising until recent years 90% of infestation. It is also emphasised
that the estimated number of rats destroyed is the absolute minimum. The total in the bodies
found column is the sum of those removed from premises by the operators and does not include
any subsequently found by occupiers on elimination of structural or incidental harbourage.
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