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New South Wales worms, flies and lice update - February 2020

NSW WormBoss Worm Control Programs

NSW WormBoss Drench Decision Guides





Guyra: Deb Maxwell, ParaBoss Executive Officer

How fast will worm populations rise after rain?
In various parts of the state there has been terrific rainfall this year, though some areas have still missed out. In many areas, not just the north, they will have been, literally, the perfect storms for barber’s pole worm. The Northern Tablelands and coastal areas, especially, have had week after week of “worm-hatching” rain falls. But were there any worms to hatch?

These falls, in “normal years” would have created a barber’s pole worm disaster of epic scale. But this year you may—or may not—see a delay. Will YOU be a lucky one or not?

With such a long period of no rain, hotter than normal conditions and bare exposed earth, most paddocks will have been almost worm-free before any rain started. On top of that, some sheep mobs will have been drenched during the dry periods, maybe even more than once. So those sheep will have had fairly low or even nil worm burdens before the rain, especially those drenched the latest and with effective drenches. To top it off, destocking has lowered the sheep population and stocking rates, and hence worm contamination of pastures, is lower.

Rainfall and warmth only hatches the worm eggs that are present, and barber’s pole worms are finicky—the eggs don’t hang around for weeks waiting for good conditions. Even with ongoing rain, if the worm population is starting at a very low base, it will take a while to build. 

But the question still remains, are YOU going to be lucky or are barber’s pole worms going to be devastating for your sheep fairly soon?

Don’t wait to find out the hard way with collapsing and dying sheep. WormTest with a larval culture and do it frequently—4 weekly—until conditions ease. 

If you haven’t had rain, or it only rained very recently (i.e. you don’t yet have green pick), consider whether an EFFECTIVE drench may be useful now in advance of any further rain—in dry situations a totally effective drench is essential (like a quarantine drench), otherwise you’ll end up going forward with only resistant worms (if you used a drench that was not totally effective in the last 6 months your sheep could already be only carrying resistant worms!)

Northern Tablelands lambing paddock preparation starts now
Northern Tablelands producers are reminded that preparation of low work-risk lambing paddocks should commence right NOW for a mid-September lambing (should have started earlier if you lamb before this). While the drought may not have officially finished—autumn could still be a let-down—the frequent continued January/February rains have filled paddocks with grass (even if it is only couch and watergrass) and weeds that will provide a perfect microclimate for worm eggs to hatch to larvae and persist to infect lambing ewes in spring. 

Look above this report!
The Worm control programs and Drench Decision Guides are invaluable for worm control. Have you looked at them lately? Choose the ones for your region.


Central West LLS

Coonamble: Jillian Kelly, DV (

The rain has been very variable around the Coonamble area with 350 mm received around Quambone, while only 30 mm fell on the eastern side of town towards Baradine.

Some people are still drought-affected and continue to hand feed, while others have localised flood damage to repair, and will have really good pasture growth once it dries out.

The showers have hung around for 7–10 days now and the days have been mild and humid. These conditions are perfect weather for barber’s pole worm to develop, and producers should be doing frequent faecal worm egg counts on their mobs in the coming weeks.

It is also perfect weather for flystrike. Producers are urged to monitor their mobs daily and treat struck sheep.  Farmers have been ringing the LLS office for advice on flystrike prevention, and I have been using the FlyBoss website and the Decision Tools to help them make decisions. Prevention is not just about chemical application and producers are urged to consider a multi-modal approach to fly prevention in their flocks.  For producers who have found struck sheep despite preventative chemicals having been applied, DPI is doing free maggot resistance testing, and farmers can pick up a collection kit at their nearest LLS office.

Forbes: Nik Cronin, DV ( and Belinda Edmonstone, DV (

Some areas across the Forbes region of the Central West have received some very good rain while other areas have missed out. If the warmth and increased moisture continue, barber’s pole worm will thrive and pose a risk to sheep. These worms have the capacity to build up their numbers very rapidly when the conditions are right. Monitoring with regular worm tests will help detect an infestation before it becomes too severe. The 'motor bike' test (i.e. gently moving sheep across the paddock to see if any lag behind) is another way to monitor what is happening in the mob.

Editor’s note: If any stock collapse during the test from weakness and lethargy due to lack of oxygen to the muscles, there is a risk of death if they continue to be pushed along and otherwise stressed. Animals that collapse are best treated on the spot with a drench and left to rest (you can carry a small bottle of drench and a syringe when mustering for such eventualities; do NOT use drenches containing organophosphates for this purpose).

Blowflies will also thrive in these warm, wet conditions and will be attracted to wet sheep. Consult FlyBoss to develop the best preventative plan for your operation, remembering to take wool withholds and other withholding periods into account when choosing a product.

Northern Tablelands LLS

Armidale: Amanda Walker, DV (

Thankfully the rain here continues. Armidale has already exceeded the 2019 rainfall total.  Consistent moisture and warm temperatures have led to increased worm activity with occasional cases of clinical disease from barber’s pole worm infection being reported.

Those producers starting to source re-stockers are reminded of the importance of quarantine drenching. Avoid introducing drench resistant worms by treating all introduced sheep with an effective drench and isolating these sheep in a small, secure paddock for at least four days after drenching. The time in quarantine will allow any eggs present in sheep to pass from the gut, and so this paddock should not be grazed by sheep while worm larvae remain viable (3 months in summer, 6 months in winter). Treated sheep may then be released from quarantine, and ideally, a WormTest performed 10–14 days after the drench to confirm the efficacy of the quarantine procedure.

Editor's note: Qurantine drenching back onto destocked paddocks with an absolutely, totally, effective drench is critical now more than ever because your paddocks likely have NO worms. Whatever you bring in will become your new worm population. Don't tke shortcuts in your drench choice on this occasion or you could make it even worse. 

Murray LLS

Albury: Mark Corrigan, DV (  

Holbrook: Eve Hall, DV (

Josie Fleming, final year veterinary student University of Sydney

Rainfall across the Eastern Murray region has been highly variable due to storm activity. Average rainfall since mid-January has been between 64–109 mm.

Due to warm temperatures and relatively high rainfall, producers should be aware of the potential increase in worm numbers. Barber’s pole worm is of particular concern as high worm burdens can be a significant cause of production losses in sheep. Producers should be on the watch for clinical signs associated with worm burden, such as pale membranes, exercise intolerance and ‘bottle jaw’ oedema, Performing a worm egg count on representative mobs is recommended to guide drenching decisions.

District veterinarians recently investigated a mob of ewes in which a small percentage were exhibiting poor performance with progressive weight loss and weakness. This mob was last drenched in November. The mob showed an average worm egg count of 840 eggs per gram (epg). A post mortem was performed on one of the ewes that was in poor body condition. A worm egg count reported a count of 5000 epg.  It was also found to be positive for Johnes disease which very likely reduced immune function and allowed the worm infection to take hold. The mob had not previously been vaccinated against Johnes disease. If producers are experiencing poor performance in their flocks, it is worthwhile investigating whether multiple issues are contributing to the problem.

Producers should also be aware that the rainfall may also bring increased fly activity. Cases of flystrike should be treated on an individual basis if seen sporadically. Treatment of the whole flock with a long-acting chemical, or crutching should be considered if greater than 1 in 200 sheep is being struck on a property.

Deniliquin: Linda Searle, DV (

In the west of the Murray region, just a few worm tests have been done. In some scouring, pregnant ewes with an unknown drench history, testing revealed mild to moderate worm burdens ranging from 20 eggs per gram (epg) in one group and up to 260 epg in another. The larval culture breakdown for another group of ewes with a worm egg count of 160 epg strongyle-type showed 12% barber's pole worm, 46% black scour worm, 40% brown stomach, and 2% large bowel worm. Another ewe group also with a worm egg count of 160 epg strongyle-type showed 54% black scour worm and 46% brown stomach worm. These worm egg counts indicate relatively low worm burdens so it may be that the scouring was due to other issues. Nevertheless, it is interesting to note the increase in brown scour worm numbers, as the black scour worm is usually the more prevalent worm in this area.

Western LLS

Bourke: Charlotte Cavanagh, DV (,

I am pleased to report that there has been some patchy areas of rainfall in the western region. We are also waiting for a flow into the Darling River, which will be great, but we are not expecting flooding at this stage. With storms about, some rain and increased relative humidity as well as drought-stressed sheep, barber’s pole worm will be something to keep a watchful eye on.

Only one WormTest was submitted in January and none in February as yet, owing to the dry conditions.

Western LLS has been putting communications out this week including several radio interviews about things to look out for after the rain. We have encouraged producers to conduct WormTests on existing stock, and certainly ask for worming history when re-stocking or accepting stock on agistment.

Greater Sydney LLS

Aziz Chowdhury, DV (

Following the devastating Gosford Mountain fire and Green Wattle Creek fire over the last couple of months, most parts of Greater Sydney has received around 200 mm of rain.  Due to severe drought conditions followed by devastation from the two mega-fires, worm monitoring activity has been at a minimum.  However, the huge rain event of last month has brought life into the pastures, and into the farms and flocks. Restocking activities have been observed.

It is most apparent that worm activity, especially Haemonchus contortus (barber's pole) will increase after the rain. Flock owners/managers are encouraged to double-check the drenching program and manage their pasture wisely to minimize worm activities. Also, look out for poisonous plants especially green cestrum and bracken fern that may cause stock loss.

For February 2020 state outlooks, please follow the links below:
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