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(3) Arrangements in the district for deratting ships, the methods used, and if done by a commercial
contractor, the name of the contractor.
(a) The burning of sulphur at the rate of 3-lbs. per 1,000 cubic feet of space for a period of
not less than six hours.
(b) The generation of hydrocyanic acid gas by various methods. For the destruction of rats
a concentration of 1ICN at the rate of 2-ozs. per 1,000 cubic feet of space is required
with a minimum of two hours contact.
(c) "1080" and "Warfarin". The employment of "1080" has been used regularly throughout
the docks for some time with highly satisfactory results both on shore and in ships. An
increasing number of ships have been deratted by this method in preference to the use of
cyanide, resulting in a considerable saving of time and cost to the shipowner.
Although satisfactory results have been obtained from the use of "Warfarin" a
suitable bait has yet to be found, particularly in granaries, with which to mix the poison,
so that rats will take it continuously in preference to grain and other forms of cereal on
which they are normally feeding.
(d) Trapping. Trapping is seldom employed save for the destruction of isolated rats which
have escaped a major poisoning operation or which have not yet established themselves.
(e) Methyl Bromide. This is a very effective and lethal fumigant which has been used in
this Port as an insecticide, particularly in the dry fruit industry. It has considerable
penetrating powers and is not difficult to disperse after an operation. It is also possible
to use this gas as a rodenticide and where there is an infestation of rodents and
insects the combined problem can be solved with one operation.
The following are the names of the firms approved for carrying out the deratting of ships:—
Messrs. Associated Fumigators Ltd. Messrs. D is infestation Ltd.
Messrs. London Fumigation Co. Ltd. Messrs. Ridpests Ltd.
RODENT CONTROL ON LIGHTERS
The control of rodents on lighters is of great importance in the general scheme for rodent
destruction in the Port of London. Apart from the fact that the transport of rodents by lighters
from place to place could be a means of communicating rodent borne disease on a major scale,
there must also be considered the discomfort and possible infection of the lightermen, as well as
the damage to cargo, resulting from rat colonies on board. The suppression of rats and mice on
lighters is given constant attention by the Port Health Authority and where infested craft are
found prompt measures of destruction are carried out in co-operation with the lighterage industry.
An essential to all rodent control work is to ensure, as far as practicable, that there are no
spaces where rodents can remain undisturbed,possibly with an adequate supply of food and water.
While it is almost impossible to deny rodents access to lighters, it is possible to deny them
accessible hiding places and the means of communication to gain access from one compartment
and another. To do this, especially with older craft, means the adoption of rat-proofing
principles which can only be done with the goodwill of the lighterage companies, the trade unions
and the Port Health Authority whose officers are always ready and willing to advise but have no
legal powers to insist on rat-proofing.
Following correspondence with the Association of Master Lightermen and Barge Owners and
the Trade Union concerned, it was decided to invite representatives of both sides to a meeting at
Guildhall. This took place on the evening of Tuesday, 14th July, 1959. About thirty-five members
of the two organisations attended and were addressed by your Medical Officer, Mr. T.L.
Mackie, Chief Port Health Inspector; and by Mr. W.G. Stimson, the Senior Rodent Inspector.
Coloured slides were shown to illustrate the various rat harbourages on lighters and examples of
rat-proofing already carried out or incorporated in new craft.
Mr. W.G. Stimson, the Senior Rodent Inspector, in his report for 1959 states:
"As a result of the joint meeting the rat-proofing measures recommended by the Port
Health Authority have been adopted by the industry and are now more or less standardised.
The objection raised at the meeting as to the removal of the deckhead linings to eliminate
the harbourage where rats can live and breed has been overcome by most firms. Instead of
treating the deckhead with anti-condensation paint and cork dusting, the principle adopted
now is to have waterproof hardboard fixed flush to the deckhead, thus avoiding the cavity
and preventing condensation over the bench in the cabin."
The method of rodent destruction to be employed on lighters is determined after initial inspection,
one of the following methods being employed — sulphur dioxide, hydrogen cyanide,
methyl bromide and poison baits.
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