Blowfly strike cases confirmed across the UK

Spring fly strike reporting has now confirmed cases in Scotland, Wales and England, according to the latest flock blowfly alert.

Sheep farmers are being advised to look for the signs of fly strike as temperatures increase.

Signs include:

  • Discoloured/damp fleece
  • Fleece loss
  • Separation from flock
  • Sick animals
  • Death (due to septicaemia, secondary bacterial infection and release of toxins)

Fly strike has been reported as far north as Ayrshire this week (22 May), adding to a list of northern cases, including three in Yorkshire and one reported case in Cumbria.

This is according to the Elanco Blowfly Tracker, an online map automatically updating when farmers and vets report a fly strike case through the National Animal Disease Information Service (Nadis)

See also: A guide to managing fluke on your sheep farm

Blowfly facts

  • Blowfly depends on soil temperatures of 9C or more
  • Life cycle lasts two to four weeks
  • Spends two to four days on sheep
  • Migrates to soil as a maggot when in its third maggot stage
  • Pupa develops in the soil and emerges as a fly after one week

Nadis has given central and southern England a medium-risk blowfly status, along with the central Pennines, and most of Wales.

Scotland remains a low-risk area with northern coastal regions such as Anglesey, East Yorkshire, Cumbria and the Isle of Man.

The first reported cases were in Hampshire on 19 April, followed by cases in West Sussex, Devon, Buckinghamshire, Berkshire and Montgomeryshire later that month.

Despite the cold spring, the first reported cases were in mid-April, whereas in 2016 the first incident was in early May.

Preventing strike

  • Discuss a preventative product with your vet or SQP
  • Dagg, crutch and shearing reduce dirty back ends
  • Tail docking lambs can reduce strike
  • Control worm burdens – discuss faecal egg counts and a parasite control plan with your vet
  • Treat lame sheep promptly – flies are attracted to wounds in feet
  • Manage fly populations by promptly disposing of deadstock, using fly traps and grazing fields that are less favoured by flies.


  • Clip entire affected area
  • Apply product to kill maggots
  • Consider non-steroidal pain relief and spray or inject to stop secondary bacterial infection
  • Discuss treatments with vet