228 
The Aberystwyth Area 
is no doubt that some afford a much longer period of protection against 
recurrence of attack than others. Some dips are obviously better suited 
for use in summer, others for winter, and too wide a use is made of 
carbolic dips during the summer without the addition of sulphur. 
There appears to be room on the market for both types of dip if their 
correct values and limitations are recognised. A sulphur dip was 
formally in use locally, consisting of 1 lb. of powdered sulphur to 10 gals, 
of water, and is said to have been very successful as an anti-fly remedy. 
Certain mountain and hill districts which are so situated as to be 
especially wind swept, seem remarkably free from maggot. Long 
tongues of hill land flanked by deep valleys and swept from end to end 
by the prevailing west to east winds seem most favourably influenced, 
and bare connecting ridges and spurs of similar aspect likewise. Any¬ 
thing in the nature of shelter whether due to a depression, or lee side 
of vegetation, etc., has a prejudicial effect. Sunny aspect has an effect 
also, especially in conjunction with the above features. 
The salt marshes, otherwise so healthy, are by no means immune 
from the pest; although open and treeless they are frequently thickly 
covered with rushes. I have also had bad reports from the sandy 
coastal margin. 
Odd cases may occur as early as April (I once saw a bad case in the 
last days of March on the S. Pembrokeshire cliffs after an exceptionally 
hot spell) but trouble seldom becomes serious until June and usually 
not until July: by mid-September danger may be considered over. 
The following are typical reports obtained from farmers and shepherds 
and refer to a period of years unless a particular year is given. 
I. A sheep walk with about 1500 sheep present during summer 
time; elevation 900—1400 feet. 
No maggots before June, then according to weather conditions. 
One or two cases daily in ordinary fine weather, but if conditions 
favourable one to two dozen cases might occur for several days, more 
especially on the lower part of the hill which overlooks a valley, lies in 
the sun, and where there is more fern. 
(I have attempted an estimate of cases for such a place, as follows: 
Period of liability: June 30 days, 
July 31 „ 
Aug. 31 „ 
Sept. 15 „ 
Total 107 or say 100 days. 
