NADIS & Elanco Blowfly Alert update

Real-time updates on blowfly risk – produced via an ongoing collaboration between Elanco and NADIS (National Animal Disease Information Service) – now show the risk level increasing to “Medium” across some regions of the country.

Richard Wall, Professor of Zoology (Ectoparasite Specialist) and compiler of the Blowfly Risk Alerts says: “As a result of recent warmer weather, the blowfly strike risk has now started to rise in southern England. Even in areas where the strike risk is still low, occasional strikes may occur, so care is needed.  Strike risk typically changes very slowly at the start of the season, but lowland ewes with dirty back ends can be particularly susceptible before shearing at this time of year.”

Regional alert breakdown 

Region Score
NW Scotland Low
E Scotland Low
NE England Low
E Anglia Low
The Midlands Med
S England Med
SW Scotland Low
NW England Low
N Wales Low
SW England Med
S Wales Low
N Ireland Low

NADIS Map key:

Low risk: no significant risk

Medium risk: 1 in 2500 animals might be struck

High risk: 1 in 500 animals might be struck

Severe risk: 1 in 100 animals might be struck


For farmers and animal health professionals seeking to guard against blowfly strike this year:

Strike reports– Real-time reports provided by farmers. This anonymous service shows genuine cases of blowfly as and when they appear on a map of the UK.

Risk warning – The partnership between Elanco and NADIS has resulted in this powerful tool that shows continuous updates on blowfly risk levels based on Met Office Data.

Combined, these tools are powerful weapons in the arsenal of any farming professional looking to strike first against blowfly.

Fiona Lovatt says “We are at the mercy of the weather, so it’s best to apply a treatment that gives you the best coverage,” says independent sheep veterinary consultant, Dr Fiona Lovatt. “The costs of inaction when it comes to blowfly strike far outweigh the costs of protection – the time to act is now.”

Farmers are being urged to ‘strike first’ with preventative treatments rather than risk devastation to their own flock.

Using protection early reduces risk later in the season by ensuring a much lower fly count as the season progresses. 1

“A lot of farmers think “it’s not in my control” because of bad weather or other circumstances,” says Kate Heller, Technical Vet at Elanco. “They’re unnecessarily putting limits on themselves. Blowfly strike is not an inevitable part of farming and can be mostly avoided with the right management strategy.”

“When farmers are looking at treatment options, they need to look for the longest protection with an IGR that binds to the fleece – It is now possible to get 19 weeks blowfly strike prevention. There are no guarantees when it comes to blowfly strike – with significant levels identified into November, an essential part of any strategy, has to ensure an early treatment that extends right through the long season,” advises Kate Heller.

Kate Heller, Technical Vet at Elanco

National Farm Research blowfly study 

Results of an Elanco blowfly study conducted in partnership with the National Farm Research Unit1 found that 99% of farmers having suffered financial losses as a result of blowfly strike. While 82% agree that the blowfly season is getting longer, with cases of strike being reported as early as February and as late as November.2

The cost 

The consequences of blowfly strike can be devastating, leading to production losses and welfare problems. By comparison, preventing blowfly strike using a long-lasting product can offer not only peace of mind but can also be economical in terms of time, money and effort.

Blowfly strike: financial losses2 Compared to blowfly treatment
£200 – breeding a replacement ewe  
£80 – loss per lamb death  
£10 – production loss per struck lamb  
£10 – labour costs handling struck animals Treatment – 50p per animal