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RODENT CONTROL MEASURES CARRIED OUT ON LIGHTERS
Since 1954, when detailed records were first kept, there has been a marked decrease in the
percentage of lighters which on inspection have required deratting and the most satisfactory figures
so far achieved are those recorded this year. Only 47 (1.4%) of the 3,294 lighters inspected needed
treatment and from these a total of 172 rats, an average of 3.7 rats per lighter, were recovered.
Together with the chemical methods of control the prime factor for the continued decrease
in the rodent infestation of lighters is undoubtably the rat proofing measures undertaken by the
Lighterage Industry following the adoption of rat proofing techniques discussed generally in 1959.
The success of these techniques has encouraged more owners to adopt them and rat proofing is
now an accepted method of rodent control on lighters.
The methods of deratting employed throughout the year were:—
1. Sulphur Dioxide gas.
2. Methyl Bromide Vapour
3. Sodium mono-fluoroacetate baiting.
The method of treatment is determined by the circumstances and degree of infestation at the time
of inspection.
Throughout the year 664 lighters were fumigated with Methyl Bromide for insect control of the
cargo and as the dosage required varies between twenty and thirty ounces per 1,000 cubic feet
according to the species of insect pest, with a twenty-four hour exposure period this is /more than
sufficient to destroy any rats that may be present at the time of fumigation.
During the year eighteen of the rats recovered from treated lighters were sent to the Public
Health Laboratory, Colindale for routine bacteriological examination. Pasturella pestis was NOT
isolated from any specimen.
SUMMARY
Number of lighters inspected 3,294
Number of Lighters without evidence 2,968
Number with negligible evidence 279
Number of Lighters treated for rats 47
Number of dead rats recovered 172
Number of rats sent for bacteriological
examination. (All results were negative
for P. Pestis) 18