The blowfly alert has now reached the highest risk possible: severe risk of strike in England, Wales and South West Scotland.

The onset of summer rain combined with high fly populations will elevate strike risk over the next few weeks, particularly for lambs. Appropriate treatment and careful inspection of flocks are therefore essential. Summer scouring is an important risk factor, so appropriate control of worms will also help to reduce the strike incidence.

The NADIS Blowfly Alert is put together with risk information provided by Professor Richard Wall of the University of Bristol. The model used to generate these predictions uses Met Office recordings of daily temperatures and rainfall, along with a detailed understanding of fly biology and sheep susceptibility to strike, to forecast the patterns of strike incidence. The model is highly accurate and tests have shown that it can effectively explain patterns of strike in sheep flocks.