25 August 1995

Fly strike risk is up after hot spell

SHEEP producers must be extra vigilant in checking stock for flystrike as the hot summer has taken blowfly populations to record levels.

The warning comes from Bristol Universitys Dr Richard Wall. He has been monitoring blowfly levels, and says incidence is four times the average this year.

Maggots of the fly cause strike in sheep, he cautions, with lambs in wooded or sheltered areas where flies are worst at greatest risk.

While the dry weather lasts, sheep are likely to be clean and strike may only be at average levels, he says. But rain and a flush of grass could cause scouring, so soiling the fleece and producing ideal conditions for fly eggs to hatch into maggots.

He says crutching soiled wool off lambs will help reduce risk of strike. But according to Scottish Agricultural College director of vet services Dr Karl Linklater it is not just dirty lambs which are being struck.

He confirms that blowfly levels are worse than normal. Given the extreme challenge, he warns that methods of prevention are not lasting as long as expected. "Pour-ons that usually last eight weeks may give only four to six weeks protection," he says.

"If you get a breakdown, repeat preventative treatment for the whole group to prevent further blowfly strike," suggests Dr Linklater.

He says producers may have to resort to dipping lambs, and even then they shouldnt be surprised if cover is reduced.