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Summer 2019 (Updated 13th May 2019)

Welcome to the Summer edition of Parasite Matters from Elanco Animal Health. Blowfly and Worms remain the focus for Farmers across the country, with weather conditions a significant factor in timing and levels of burden.

Courtesy of the Met Office

Weather patterns

  • Met Office Data shows that during March there was above average rainfall (compared to 1981-2010) up to 200% of average in the darker blue areas.
  • This increased rainfall, coupled with the warmer than average grass minimum temperatures (2°C higher on average), will have resulted in conditions that favour both the worm and fly populations early in the season.
  • April continued to be warm but with drier conditions, with average rainfall in the West and below average in the East.

Courtesy of the Met Office

Blowfly strike

  • So far May has been a colder month, but with humid conditions forecast for mid May the risk of blowfly strike will increase rapidly.
  • Applying preventative treatments early, will provide the best control for your flock. One application now of CLiK™ EXTRA can cover to the end of September (19 weeks).
  • Multiple reports of blowfly strike have been received across the country.
  • The NADIS risk alert is already at medium, with an update expected mid May.

Courtesy of the Met Office


  • The biggest challenge from a worm point of view remains Nematodirus in naïve lambs, which due to the unseasonal weather earlier in the year, had a much earlier hatch, seeing cases reported as early as 1st March.
  • The majority of the UK remains at ‘very high risk’ on the SCOPS Nematodirus forecast.
  • High efficacy and low levels of resistance make grp1 BZ white drenches the treatment of choice

Worms/drench checking

  • Watch out for other worms beginning to appear and with them variable resistance patterns.
  • Drench check after every treatment to see how many worms have been left behind. Watch the ‘How to Faecal Egg Count’ video.
  • Plan for your Zolvix™ mid-late season break dose to remove these left over worms and make the most of the late season grass.

Parasite Matters Archive

Parasite Matters Spring (published March 2019)


Watch how farmer Mike James incorporates Vecoxan into his coccidiosis control programme