Studies on the feeding patterns of the sheep headfly Hydrotaea irritans (Diptera, Muscidae) in Great Britain

Serum-precipitin tests carried out on the stomach contents of laboratory maintained and field-caught Hydrotaea irritans showed that a positive result could be obtained for at least seven to 10 days after feeding. Eye, nasal and salivary secretions, even if undiluted, did not give a precipitin response in these tests. Field results from over 3000 flies thus indicate that 20 to 55% of the active fly population had taken a blood meal within the previous 10 days: 75 to 100% of these had fed on cattle blood and 15% or less on sheep blood. Significantly lower feeding levels were obtained from flies collected within plantations, indicating a protracted resting phase in woodland. From "fly feeding areas" high blood-feeding levels were shown from early July, as ovarian development begins. Early feeding rates were similar in both sexes.