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habits above-mentioned. From these investigations it is now
believed that flies perform the chief role in the spread of summer
diarrhœa. They walk over excreta, some of which may be from
previous cases of diarrhoea, and then walk into the baby's milk, or
other food, with the natural result that the consumer takes the
disease.
"If you want to stop or lessen diarrhoea some means should
therefore be taken to get rid of flies. There are two distinct
methods, viz.: (1) Killing individual flies with fly papers and
poisonous fluids, and (2) destroying their eggs and larvae. This
last method is by far the best and has been adopted most successfully
in the case of mosquitoes. Killing individual flies is very
useful but for one which you destroy this way you can kill thousands
by the second plan. A consideration of the life history of the fly
will show why the first plan is not likely to succeed.
"In the spring the female fly lays her eggs on manure heaps,
ashpits or any collection of moist refuse and lays about 120 eggs
at each sitting of which there may be several. From these eggs in
the course of a few hours, especially in the presence of heat and
moisture, a maggot or grub issues and feeds on the filth it lives in
and in about five days becomes a chrysalis which is a 'minute
rolled up bean like body' with a hard covering about ¼ inch in
length; in another five days the fly emerges from the chrysalis
and begins searching for food. If one could stop these breeding
places in and about houses the number of flies would be enormously
reduced and means should be taken by posters and handbills to
draw the attention of householders to the necessity of scrupulous
cleanliness if flies are to be got rid of. The dust should be collected
in covered receptacles, frequently removed, no garbage of filth of
any sort should be allowed to lie about yards, all of which should
be properly paved, no unused or waste food should be allowed to
lie about unprotected and all food which is put by for use at
another time should be kept in cupboards to which flies have no
access. Milk both in milkshops and homes should be very carefully
covered and in addition to this fly papers freely used.
"I recommend therefore that I be instructed to draw up a
small leaflet containing the life history of the house fly, the diseases
which are liable to be spread and the best methods of getting rid
of them, and that one of these be distributed about the latter end
of May or beginning of June."
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