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(2) Temperature of Rooms.—Warmth and Cooking.—A warm room greatly favours flies, and
this is especially the case in Autumn, when cold nights begin to prevail. Numbers of observations
have been made in this connection with regard to use of coal fires and to the amount of cooking
carried on. Thus the influence of the "week end" is very apparent in the figures which the inspectors
have recorded. This point has been noticed by all the inspectors; one of them, Mr.
Lewis, has worked out the daily average number of flies, at a particular place of observation, for
the week end (Friday to Monday) throughout the summer and found it was 26 ; the corresponding
daily averages for other divisions of the week were, 14 (Monday to Wednesday) and 8 (Wednesday
to Friday). Doubtless the cooking operations of the week-end and perhaps to some extent also the
larger use of rooms on Saturday and Sunday are in the main responsible for this phenomenon.
Washing-days exert also a distinct influence, and, in one instance, the preparations for a wedding
appreciably increased the number of flies. Premises such as bakehouses and cowhouses, which
are always at a comparatively high temperature, are favoured places of refuge for flies during
the Autumn and Winter months.* Cold and rain, needless to say, have an opposite effect to
atmospheric warmth, and their influence is mainly rendered apparent in causing flies to have
resort to houses when the temperature falls, or when it is wet.
(3) The improper storage and insufficiently frequent removal of house refuse exercise marked
influence. For example, in the back yard of a house not far from one of the cowsheds (Centre 9)
there were always far more flies than in the cowshed itself—a fact no doubt attributable to the
presence of an old dust-bin, in which considerable quantities of refuse were allowed to accumulate.
A similar experience was forthcoming from the neighbourhood of the Knacker's Yard. The clearing
of roadways, channels and street gullies near houses also exerted appreciable influence. It was
found, moreover, that houses in streets down which dust-carts or manure carts passed were
especially infested with flies ; in numerous instances it was clear that this constituted an important
factor in the promotion and maintenance of fly nuisance.
(4) Aspect and Elevation of Room.—A sunny aspect exercised great influence on the number
of flies, while very dark rooms were comparatively free from them. Ground floor rooms yielded more
flies, cateris paribus, than rooms on higher floors. Thus around Centre 10 the daily average for
12 ground floor rooms was 25.5, for 13 first-floor rooms it was 12.7 and for 12 rooms on the 3rd and
4th floors it was 12. Several of the places of observation around this centre were in County
Council Dwellings, and the number of flies obtained in rooms in those dwellings compared, it was
found, very favourably with the numbers caught in other premises in the neighbourhood. The
superiority of the Council's dwellings as regards sanitary conditions and the better supervision
exercised, by tenants and by superintendents and caretakers, no doubt accounts in large
measure for the small number of flies found in them.
(4) Position of Fly Paper.—As was of course foreseen, the position of the fly paper materially
influenced the number of flies caught. The numbers were larger when the papers were hung in
places where the light was good, especially, if the spot chosen happened to be near the centre of
the room. One of the inspectors was told that the smell of gas attracts flies, and the number of
flies found near a gas-house was certainly larger than might have been expected, but the opportunity
of further investigating the matter did not present itself.
(6) Open Windows.—A factor of importance proved to be the influence of open windows.
In premises where the doors and windows were kept closed during the greater part of the day,
comparatively few flies were caught. This was especially noticeable in certain cases in which the
family were at work all day, or went "hopping" for a few days in the country. On the other hand,
when it chanced, owing to the desire of the occupiers for fresh air, that windows were left widely
open, the rooms were especially infested with flies. The fact that flies were continually invading
a room from without was rendered particularly clear in the case of a barber's shop used as a place of
observation. The shop was clean and no cooking was carried on ; there was indeed no ascertainable
special source of attraction for flies, except the presence of apparatus for providing hot water and
the fact that the shop front consisted almost entirely of glass. The shop was, however, on the
ground floor of a block of high buildings and was just opposite the opening of a street leading .to
some stables. Flies travelling westwards from the stables would impinge upon the block of buildings
and the barber's shop constituted in fact a sort of fly trap. Although many thousands of flies were
caught, day by day, the supply was continually renewed, presumably from the stables ; this
process of renewal, according to the occupier, was especially in evidence each morning when he
threw open the doors and windows of the shop.
Attempt was made in connection with some of the centres to study the influence exerted
by prevailing winds. This was found to be less marked than might perhaps have been expected.
At one centre the places of observation to the North East suffered less than those to the South
West, but the former were separated from the centre by a canal, and there were other reasons for
the observed differences. Yet even here it was found that the places of observation to the North
East of the centre especially suffered when the wind was in the South West.
(7) The influence of certain special sources of attraction in determining quantity and character
of flies.—The study made of the conditions obtaining in places of observation surrounding the Jam
Factory seems to suggest that numbers of flies, in excess of those ordinarily present, were observed
in the neighbourhood, when the characteristic smell of jam making was specially pronounced. On
the whole, however, the influence exerted by the Jam Factory was less considerable than it had been
anticipated would prove to be the case. Early in the enquiry a disturbing influence was found to
* Even in the depth of winter (January, 1908) considerable numbers of flies were found in the cowsheds at Centre 9.