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South Australia worms, flies and lice update - March 2017

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Adelaide: Colin Trengove, Sheep Health Lecturer (UA Roseworthy campus) (

The weather pattern over the past month has settled into a more typical autumn, suiting the commencement of grape harvest. However, spasmodic rainfall has continued to be a feature, resulting in abundant green feed in much of the 400 mm plus rainfall regions.

This contributed to the persistence of many less desirable plant species such as melons, heliotrope, lovegrass, wireweed and caltrop. The positive outcome is minimal supplementary feeding has been required and pregnancy rates should be very good given prevailing ewe body condition.

A negative is the consequent higher than usual worm egg counts for this time of year. Two thirds of mobs monitored between the upper south east to mid-north and across to the lower Eyre Peninsula have recorded counts worthy of a drench. These results have been independent of age, sex or pregnancy status. Isolated reports of Haemonchus species have also been evident. I discovered, during a recent visit, that Ceduna has received 200 mm rain this year and producers reported unusual instances of significant worm infestations.

It illustrates that one cannot assume that good feed and body condition negates the opportunistic nature of worms. Worm egg count monitoring is even more relevant when conditions suit worm larvae survival on pasture regardless of season or location.

Another observation across several flocks over summer/autumn has been the presence of lungworm, causing significant pneumonia and pleurisy. Abattoir surveillance has identified this in many cases, while on-farm post mortem investigations and subsequent personal follow-up of sheep at the abattoir has also been used to confirm this diagnosis.

Lungworm is not normally reported with regular faecal egg count monitoring because it requires a specific test to be performed. If you suspect lungworm or have had positive abattoir surveillance reports it is worthy of further investigation as it could be causing significant unapparent production loss. The presence of snails on pasture that act an intermediate host for some lungworm species can be an indicator, while coughing and ill-thrift are other signs. Not all drenches are effective against lungworm and so a further incentive for follow-up investigation.

Blowflies have also been a feature of the moist and humid conditions over summer/autumn and so frequent checking of mobs for flystrike has been an extended activity for many producers. A temporary shortage of flystrike chemicals occurred in early spring as the prevailing conditions forebode a bad season for flies. The only thing that we can be sure of is that seasonal conditions and parasite activity are subject to change and require ongoing close monitoring.

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