View report page

34
removed or carefully covered before spraying must afterwards remain
covered, since most flies will live long enough to reach it, even after
settling upon a sprayed surface. The use of D.D.T. 'bombs' would
of course intercept this movement at once, but would be unsafe in the
presence of food and should hardly be needed in its absence. The
best way to hasten the effect of D.D.T. upon flies is to add to the
spray-mixture a 'knock-down' agent such as 0.05% pyrethrin.
The third principle in handling D.D.T. is to realise that, although
poisoning by D.D.T. is exceptionally rare in man, certain precautions
are necessary in its use. Gloves and overalls should be worn by the
operator in spraying, and the hands should be completely washed after
work or before eating. Where a fine spray is used indoors, a gauze
mask is advisable. In addition, care must be taken not to contaminate
foodstuffs with D.D.T. since, although little harmful to man externally,
it will cause gastric symptoms if swallowed.
In the Richmond Public Health Department full advantage was
taken of D.D.T. from the earliest moment of its release. A number
of local experiments were made, and it was seen at once that the chief
service of this new chemical is likely to lie in the eradication of bed
bugs by thorough spraying. The spray-mixture favoured at present
contains both D.D.T. and a small fraction of a 'knock-down' agent.
DISEASES OF ANIMALS ACTS.
In Richmond Park, four hundred and forty-five sheep were
dipped, and the necessary certificate was furnished to the owner of the
animals.
In controlling the movement of cattle to or from infected areas,
two movement licences were issued, and six countersigned.
RATS AND MICE (DESTRUCTION) ACT 1919 AND
MINISTRY OF FOOD INFESTATION ORDER 1943.
During the year 170 complaints were received from occupiers as
to the presence of rats on their premises, and the work of tracing and
isolating the breeding-places of the rats entailed 836 visits.