The duration of life of the fly is not long. In the winter most
flies die, the remainder hibernate, and at the return of warm
weather produce the first broods of the summer.
PREVENTION.—The measures which should be adopted to
prevent the spread of disease through the agency of flies are very
similar to those which have been applied with so much success to
preventing the spread of malaria by means of mosquitoes, and
consist in (1) destroying them during the larval and pupal stages
of development (2) destroying them when fully developed, and
(3) protecting food against contamination.
It will be remembered that the chief breeding places for flies
are manure and any collections of garbage.
In Hackney there is a large number ot stables for horses and
cows. These are provided with dung-pits which are mostly uncovered,
thus allowing flies to enter freely and deposit their eggs.
If such manure is left undisturbed for nine days, the eggs will have
become fully developed flies; so that in order to diminish their
number, it will be most effectual to apply preventive measures
during the development stages. In the first place, the dung pit
should be kept covered, so that, if possible, flies may not enter and
deposit their eggs. The larval may be destroyed by adding chloride
of lime to the dung or by spraying the same with a solution of
ferrous sulphate, two pounds to the gallon of water. Both of these
will destroy the larvae and so prevent their developing into adult
In all cases, stable manure should be removed twice a week,
and not deposited within a mile of the Borough, unless the manure
is treated with one of the insecticides above mentioned; and where
the object is not only to prevent development in the Borough,
but elsewhere, the insecticides should be always used when the