Fly Strike - The Accidental Smallholder

Fly strike is a horrible thing for any flock owner to deal with and can easily be fatal to the sheep if not detected early enough.

Blowflies (metallic green or blue in appearance) lay their white, seed-like eggs in the wool, often at the rear end or around the horn base but it can be anywhere. When the eggs hatch, the maggots will start to eat into the skin and flesh of the sheep.

The blowfly “season” used to be May to September but, with climate change, it can happen outwith this period, so flock owners must be vigilant. Be prepared and always have the chemicals available to treat fly strike in your medicine cabinet.

If the weather is mild and still and the spring grass is perhaps leading to sheep having loose faeces and therefore dirty bottoms, check your flock twice daily for signs of affected sheep. Continue this routine throughout the fly “season”.

The risk of strike can be reduced, but not eliminated, by dagging i.e. cutting away soiled wool from the sheeps’ back ends.

Detecting fly strike

A sheep that has been fly struck will display abnormal behaviour – it may be on its own, not grazing or cudding but looking preoccupied; it may be rubbing along a fence or wall; it may be stamping its feet, kicking or biting at itself. If you are at all concerned – don’t wait until tomorrow, catch the sheep and examine it closely. There is a distinctive smell associated with fly strike.

Treating fly strike

Once you have found where the strike is, cut away all the affected wool and treat with your chosen chemical – use gloves and massage it well into the affected area. We use Crovect but there are others available.

You then have the satisfaction of seeing the maggots fall off the sheep. Make sure all the affected wool is removed and treat the skin with Terramycin spray. Some folk like to apply an antiseptic cream to protect the area.

Check there are no other areas of strike. If the flesh is damaged, take your vet’s advice – s/he may advise a long-acting antibiotic injection. Mark the sheep so that you can check her daily.

Routine treatment

Sheep can be routinely treated during the “season” with pour-on or spray-on chemicals; usually the first application will be made after shearing then every six weeks thereafter. These chemicals are pretty nasty, so try to avoid using them routinely before shearing – for the sake of your shearer and those who will handle the fleeces after shearing.

Strike First expert report

Produced by Elanco Animal Health, this report addresses some of the barriers to preventing blowfly strike and the potential consequences of not acting.

This report combines the knowledge of an expert panel with the latest information on blowfly strike prevalence in the UK and new research on the experiences of farmers in dealing with this unpleasant, yet familiar, parasite.

Download Strike First - PDF, 885KB

Ticks, Keds, Lice and Fleas

These biting insects are generally controlled by chemicals administered to control other external parasites.