226 
The Aberystwyth Area 
be missing is often omitted or slurred during busy times, it is not 
surprising that some are overlooked and either die undiscovered, or 
get into such a state that treatment is difficult, and sheep so injured 
are long in recovering. Many farmers lose from one to four sheep 
annually from this cause. 
The wooded valleys are, as might be expected, the worst affected, 
and maggots are there an annual occurrence, though in degree in 
accordance with weather conditions. Many farms have a wide vertical 
range and may include: 
1. Riverside meadow varying from good grass to rank gorse and 
rushes. 
2. Wooded slopes, with fields interpersed. 
3. Open upland which may either be bare, or more or less heavily 
covered with fern and gorse. 
The higher and barer the grazing area, the less liable are the sheep 
to attack, but the presence or absence of fern and gorse are most im¬ 
portant factors for several reasons: 
(a) Sheep that graze among fern are liable to become wetted and 
to remain wet longer than those grazing in the open, and damp sheep 
are more liable to attack than dry ones. Damp sheep, especially if 
untrimmed and at all dirty, give off a strong odour which doubtless 
attracts the fly. Shepherds say that sheep grazing among fern are 
especially liable to attack about the head, neck and shoulders, as these 
parts are wetted by being pushed among the fern, which, together with 
the grass that generally grows in its shelter, retains dew and rain water 
long after the barer portions of the land have dried. 
( b ) Sheep attacked in such situations have a much greater chance 
of avoiding detection, unless very carefully hunted up. 
(c) The flies doubtless find shelter among rough vegetation. 
Fern and gorse, or a combination of these, but more particularly 
deep fern, extend the danger zone for maggot attack for a great distance 
upwards. A ferny mountain means trouble with maggots. There are 
summers, cold, wet, or windy, during which maggots are practically 
unknown on the higher sheep walks, and but little is seen of them even 
in the wooded valleys and lowlands. There may be a short period 
during which attacks occur, and the period may be of considerable 
duration, or a series of outbreaks may occur. All depends upon 
atmospheric and climatic conditions, which may be strongly modified 
by the presence of woodland, gorse or fern, etc., and by the attention 
of the farmer and shepherd. 
