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sufficient for their welfare. They are erratic in their feeding habits and may eat a very small
amount at a number of places — not necessarily the same each day. This means that very many
small baiting points are necessary in applying control measures with poison. This also tends to
rule out the use of the more acute poisons.
Where there is unlimited harbourage, both structural and incidental as found in warehouses
with large bulk stowages of varying commodities, plus a reasonable food supply, there appears to
be a very diminished range of activity from the nesting quarters. Therefore, a high percentage of
an infestation living and breeding therein do not come out to accept the baits at the baiting
sites which are limited by the size of the stowages, or by congestion often found in other types
of premises.
Many of the complaints of mice infestation are received from offices, and the cause can
usually be traced to the careless or thoughtless disposal by the staff of food scraps. It is a
common occurrence to find food wrappers, fruit parings, odd uneaten scraps, and milk bottle tops
with cream adhering, thrown down in inaccessible places behind fittings and machines. Alternatively,
it is put into waste paper baskets where, as a rule, it remains all night to attract and
provide the necessary food for the existence of mice.
The popular belief prevalent that rats and mice do not live together in the same premises is
not strictly true. If the environmental conditions provide suitable harbourage and a sufficient
supply of food, both species will accept the conditions offered, though as a rule they will live
away from each other in separate sections. If, however, the facilities for their welfare are diminished,
it appears to be a question of the survival of the larger species, and the mice disappear.
The nucleus of mice infestation is often imported into premises, and in the case of catering
establishments many instances have been seen where this has occurred via sacks of vegetables
and crates of eggs.
To illustrate further the decline in rat infestation and the comparable rise in mice infestation
the following summary and graph is included as a useful record. The estimation of the number of
rats killed is based on the amount of poison bait consumed. The calculation is however based on
Common rat extermination, and as 90% of surface infestations were of Ship rat character the estimate
is conservative, and could reasonably be increased by 25%. The latter being a smaller and
finer built creature, it consequently consumes less food, and a smaller quantity of poison bait
constitutes a lethal dose.
The total in the bodies found columns 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.

The low level of Common rat infestation is in no small measure due to the systematic periodical
control measures applied in the City sewers at quarterly intervals. It is the purpose of
these treatments to check the build-up of the rat population in the sewers and thereby assist in
preventing infestation of surface properties from this source via defective drainage.
Having carried out 21 treatments over a period of five years, principally with Sodium Fluoroacetate
'1080', it was suggested that Fluoracetamide, technically known as '1081', might prove
advantageous as an alternative to '1080', and after discussion with the Scientific Officers, Ministry
of Agriculture, Fisheries and Food, it was agreed that four direct controls be applied in a
similar manner to the '1080' treatments.
15.