Greenbottle adult on a leaf© Roger Tidman/FLPA / imageBROKER/REX/Shutterstock

Vets are urging sheep producers to take action to prevent against the parasite blowfly after the first cases were reported on two farms in West Sussex.

With Met Office forecasters predicting warm, sunny weather interspersed with long spells of rain for much of the UK in May – ideal conditions for blowfly larvae to flourish – vets warn the challenge will be heightened.

The warning comes after new findings from an Elanco survey showed 94% of sheep farmers have been caught out by the parasite in the past and 41% said the parasite is striking earlier in the year.

See also: Advice on treating blowfly

Overwintered blowfly larvae hatch when temperatures reach 9C or higher. Once hatched, high temperatures combined with humidity create a microclimate in sheep fleece that attracts adult flies to lay eggs.

Fiona Anderson, technical consultant manager at Elanco Animal Health, says there is no point taking any risks with blowfly.

“It’s crucial [farmers] do not get complacent when it comes to blowfly – the costs of inaction can be devastating.

“It’s an extremely distressing disease to see in sheep, and obviously for the sheep themselves, so there’s no sense in taking the risk.

“Farmers should take control of the situation before blowfly strikes their flock by using preventative products with full-fleece protection.”

Another benefit of using a preventative product early in the season is that killing flies from the first wave of insects reduces the total number of flies for the rest of the season, she adds.

Don’t wait to treat

Ms Anderson says waiting for clear signs of blowfly before treating is “a gamble”.

“Farmers are extremely busy and blowfly strike can establish very quickly, so it would be very easy to miss an affected sheep.”