C. L. Walton 
229 
allowing 
40 days without cases 
40 „ with 1 case daily = 40 
10—12 „ „ 5 „ „ = 50— 60 
8—10 „ „ 10 „ „ = 80—100 
Say 100 days with a total of 170—200 cases. 
1500 or 1600 sheep and 160 cases would enable us to estimate say 
10 % for the season. Many of these would be slight and the fleece 
unbroken.) 
On lowland farms the percentage might be 20 % or higher. 
II. Farm part bog and salting, and partly pasture along the 
margin of wooded slopes; 200—300 acres, about 200 ewes kept. 
Maggots very troublesome especially on the bog land. 
III. One of the most experienced shepherds speaking of the flanks 
of Plynlymon states that several years may elapse during which very 
few cases will occur, then comes an especially hot time with showers 
followed by an outbreak involving the whole area. 
Larvae of L. sericata obtained near Talybont on June 1st, 1915, 
from a ewe that had just died from their attack, hatched June 27th—29th. 
Very severe attacks took place during suitable weather July 1st—7th, 
1914, and June 1st—9th, 1915. 
Sheep maggots are known locally as Cynron. 
Blue bottles (Calliphora erythrocephala Meigen) undoubtedly cause 
some trouble, but the chief loss is due to L. sericata. 
Sheep Nasal Fly ( Oestrus ovis). 
Considerable difficulty was experienced in obtaining accurate in¬ 
formation regarding this sheep pest. Enquiries made at the commence¬ 
ment of the work informed me that losses had occurred within the 
Area about the years 1900- 1904. I subsequently made extensive 
enquiries, and after obtaining data from thirty-five sheep farmers and 
shepherds, have arrived at the following facts. A severe outbreak 
commenced in the summer of 1900 resulting in heavy losses during the 
spring and early summer of 1901. Trouble and losses continued during 
1902—3, and apparently the disease waned and practically ended in 
1904. The outbreak was of a very sudden nature and most of my 
informants stated that this trouble had not been seen before or since. 
Sheep men in the south of the Area declare that the trouble had come 
