THE SEASONAL PATTERN OF SHEEP BLOWFLY STRIKE IN ENGLAND AND WALES

Information on 4049 cases of sheep blowfly strike on 495 farms in Engl and and Wales was gathered in a longitudinal survey conducted in 1991. The breech was the most commonly infested area, accounting for 70.9% of all strikes recorded. Body strikes accounted for 19.7% and foot str ikes 11.4% of all strikes. Early in the season the incidences of both breech and body strikes were higher in ewes than in lambs, but from Ju ne to October lamb strikes predominated. The incidence of foot strike was greater in ewes than lambs throughout the year, with a peak incide nce in September. Regional differences in strike incidence were eviden t; the highest overall incidences were recorded in the southern region s of England where peak incidence occurred earlier in the year. The hi ghest monthly incidence risk was recorded in August in the south-east of England where there were 14.2 strikes per 1000 lambs and 4.0 strike s per 1000 ewes at risk. The importance of faecal soiling and ambient temperature are discussed.