High potential for blowfly strike this autumn
2nd September 2022
Sheep farmers are being warned of a continued blowfly strike risk this autumn, with the likelihood of a period of mild and wet weather.
According to Matt Colston, ruminant technical consultant at Elanco Animal Health, the long, dry summer has helped to keep fly populations at bay. But if we now experience warm autumn temperatures, coupled with some rain, we could see a significant uptick in blowfly strike cases.
To protect against late season fly strike, Mr Colston recommends that farmers who treated their flock with preventive fly control in the spring, stay vigilant and apply a top up treatment of an Insect Growth Regulator (IGR) as the period of protection runs out.
“Flies need warmth and moisture to reproduce, both on the pasture and the sheep’s fleece, which is why the dry conditions have led to a lower strike risk this summer, compared to last year.” he says.
“However with the Met Office predicting a warm and unsettled forecast for early autumn, it’s important to beware of the continuing risk to avoid being caught out. Particularly as the protection period from earlier fly control treatments is likely to be coming to end.”
Mr Colston advises choosing an IGR with a short meat withdrawal, such as CLiKZiN, on fat lambs heading to market. This delivers eight weeks of protection with just seven days meat withdrawal.
“For sheep remaining on-farm, CLiK or CLiK Extra may be a more suitable option, offering longer protection, as in the right conditions, blowfly strike risk can extend right through to the end of November,” he says.
For long lasting, full fleece protection, the IGRs should be applied using a calibrated gun with fan nozzle in a band approximately 10cm wide (the 4 stroke method). The total dose should be applied one quarter at a time using the four stroke method as follows:
- Mid-shoulder to middle of back
- Middle of back to top of tail
- One side of tail to crutch
- Other side of tail to crutch
Mr Colston encourages farmers who have been hit with a case of blowfly strike to report it via the Blowfly Tracker www.farmanimalhealth.co.uk/blowfly-tracker to help farmers and the wider industry stay alert to continuing risk this autumn.
For further guidance on blowfly strike prevention and treatment, please visit: www.farmanimalhealth.co.uk/sheep/sheep-blowflies
