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and Malathion, etc., to counteract the development of organismal
resistance.
During the year the department dealt with 75 cases of dirty
and verminous premises compared with 88 in 1960. The disinfestation
staff sprayed 240 rooms and contents as compared with 256
last year. In 8 cases the bedding and effects were removed to the
Council's disinfecting station for treatment by steam or formaldehyde.
Of other pests which necessitated the treatment of 1,826 rooms
and 98 external areas, the following initiated the greater number of
complaints.
Ants. Ants carry no disease but their presence in human foodstuffs
is objectionable.
Foods of a relatively high sugar content are particularly attractive
to ants and the insects are prepared to go to great lengths in
order to obtain a sufficiency for their community.
In the main, the 47 complaints received concerned either the
black garden ant (Lasius niger) or the yellow meadow ant (L. flavis),
the workers of which will gain access to houses through cracks in the
walls or floors, over sills or through window frames in search of
food and 57 treatments involving 127 rooms and 23 external areas
were carried out to combat the reported nuisances.
One of the commonest of ants, the very small red House or
Pharoah's ant (Monomorium pharaonis) was also the cause of a
number of complaints.
This species, being of tropical origin, is incapable of breeding
in England without artificial heat. A temperature of approximately
80°F is considered to be ideal for its propagation and ipso facto il
is found infesting bakehouses, restaurants, hospitals and houses
especially in larders and kitchens and nests may be found behind
wall plasters, behind pipes or ovens, in heating ducts and undei
floor coverings and foundations.
As in previous years this pest was encountered at two of the
large hospitals in the Borough where, despite intensive investigation
the sources of infestation were not located.
The total number of treatments carried out in respect of this
ant was 57, an increase of 3 over the previous year.
Although the treatments which involved 391 rooms effected
a reasonable measure of success, it must be stated that complete
control can be achieved only by the destruction of the colonies, for
once ants become established in a building, complete elimination
is extremely difficult. Locating each individual nest, especially in
old buildings, is not only extremely difficult but commercially im