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

NSW WormBoss Worm Control Programs

NSW WormBoss Drench Decision Guides






Central West LLS

Condobolin: Hanna Dobell, DV (; Georgia Grimmond, DV (

The drought really helped to reduce the environmental contamination of worms on pastures. This provided producers with the opportunity to get on top of worm numbers, which is reflected in the relatively low to zero worm burdens.

However, the tide can turn quickly! An area where I most commonly see a break down in worm control is when producers buy in stock, particularly trade lambs, and fail to administer an effective quarantine drench. This not only provides an opportunity for worm numbers to rise but also increases the risk of introducing resistant worms onto your property.

Quarantine drench all new sheep with drenches that contain four active ingredients, including one new class anthelmintic e.g. Derquantel, combined with abamectin (Startect) or Monepantel (Zolvix), and back them up with a Levamisole and BZ (white drench) combination. This is not the time to be stingy with your drench! After drenching, isolate sheep for a couple of days in a holding paddock, then let sheep out onto a contaminated pasture/paddock. Ideally, producers should also follow up with a WEC 10–14 days after drenching to ensure treatment efficacy.

Coonabarabran: Kate Atkinson, DV (

The phenomenal season we are having this year is likely to be accompanied by phenomenal worm burdens. The most susceptible class of sheep are weaners, so a spring drench with a combination product (at least 3 active ingredients) or a newer class drench such as Zolvix (Monepantel) or Startect is warranted. Moving weaners to a low risk paddock following drenching is also recommended for effective worm control. These are paddocks that have been spelled for 3 months (i.e since the start of lambing). Performing a worm test 10–14 days following drenching will indicate whether the drench used has been effective. Worm tests should be repeated every 4–6 weeks between weaning and shearing to ensure good worm control management. The weather conditions for barber’s pole worm are particularly favourable as we move toward spring, so effective worm management programs are necessary to minimise losses.

Coonamble: Jillian Kelly, DV (

Conditions at the moment are the perfect in-between weather for worms. It's just cold and wet enough for black scour worms, and there have still been some warm days and rain to keep barber’s pole worm simmering along as well. It seems that the days of getting a long cold winter to break the barber’s pole worm lifecycle are gone! Many producers are doing the right thing and worm testing at the moment, and choosing strategic drenches. We have mainly seen the black scour worms to the south of Coonamble, around Gulargambone and Armatree. With more rain forecast this weekend, producers really need to bring their A-game to the worm management part of the enterprise right now, otherwise they may be facing "Worm-ageddon" come spring and summer.

It is important that producers choose the "Gold plus Typing" test on the NSW DPI wormtest submission form (or ask for a larval culture from other WEC providers). It costs a bit extra, but you will know what sort of worms you are dealing with and can make appropriate decisions.

A cattle producer I was speaking to recently was commenting that his cows didn't seem to be doing as well on the pasture as they should be, considering the quality and quantity. While there are many different disease processes that could be going on in these animals, one possibility is definitely Ostertagia. Cattle that were nutritionally stressed during the drought seemed to have lots of Ostertagia larvae buried into the wall of the abomasum (on post-mortem their abomasums look thickened and leathery). These cattle could still be carrying these burdens if they haven't had a good drench, and they will be having an impact on nutritional absorption and the performance of the cattle. A faecal egg count won't be as useful to diagnose this problem in adult cattle (as they are immature larvae and won't be excreting eggs, and cows have a strong worm immunity), but the moral of the story is to be aware that adult cows can suffer from worm problems, especially during or after nutritionally stressful periods!

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

As with much of the state, the wet conditions continue in the Forbes area. We look forward to a plentiful spring. Associated with these conditions is an ideal environment for worm survival on pastures. Producers need to be drenching weaner sheep onto a 'low risk' paddock with an effective broad spectrum drench. Do a worm test 10–14 days later to ensure the drench is effective. Remember the old saying 'the most expensive drench is the one that doesn't work'.

We had an interesting case with 90% of unmarked lambs: ill-thrifty, scouring and dying. Preceding the clinical signs these lambs had been held in a small paddock that was used as a containment lot during the drought. Nematodirus was a suspect on the list of possible diagnoses. These worms rarely cause a problem, however, they produce a very tough egg that will survive dry conditions and accumulate through the drought. When it does rain, there is a mass-hatching of the eggs, providing heaps of infective larvae for sheep to ingest. Lambs seem to be particularly susceptible.

Nyngan: Kelly Wood, DV (

After a few dry years without a lot of worms to contend with, we are coming into a prime spring conditions for barber’s pole worm.  Once average daily temperatures rise, regular rainfall that grows grass will also allow worm eggs to hatch and build up rapidly on the pasture. Brown stomach worm can start developing with daily maximums as low as 8°C, black scour worms at about 12–15°C, but barber’s pole need 18°C, however, the latter make up for the late start by being highly fecund, laying up to 10,000 eggs/day, so careful management under ideal conditions is important to prevent them having an impact on your flock. Larval pick-up will be on the rise over the next few weeks so it’s a good idea to do a worm test now to get an idea of the degree of pasture contamination on your farm. Choosing the right drench will also be very important in controlling barber’s pole on your property. Research during a drench trial five years ago has shown that resistance is on the rise in the central west with 100% of properties showing barber’s pole worm resistant to abamectin and ivermectin, and 50% of properties with moxidectin-resistant barber’s pole worm. Central West LLS is about to embark on another round of drench trials this spring, so watch this space on updated resistance profiles in your area! In order to keep on top of barber’s pole this spring and summer, we need to work smarter not harder so get worm-testing and get in touch with your district vet if you would like any advice on drench selection and timing. 

It’s also likely to be a big season for flies with people already noticing flystrike on their properties. Careful planning of your flystrike prevention strategies now will save you big headaches in the coming months. The FlyBoss and WormBoss websites are both great resources to assist you in developing your parasite control plan. Be on the lookout for buffalo fly, especially if you are around the Macquarie Marshes. Central West LLS would be very interested to see samples if you are able to catch them. 


North West LLS

Northern Slopes: Ted Irwin, DV (

Unfortunately, I have hardly seen any sheep, let alone worms in the last few weeks. Lots of cattle trading going on as people attempt to re-stock or just get some cash flow back into their business post-drought. No worm issues seen in either species. Conditions have been pretty good for winter crops here in the NW Slopes and so most fattening stock are on winter fodder crops or, if not, have abundant legumes within grass paddocks. If the predicted wet spring arrives then there should be some parasite issues emerging as temperatures get warmer.


Murray LLS

Albury: Mark Corrigan, DV (

Deniliquin: Linda Searle, DV (

The eastern end area of Murray Local Lands continues to see the best seasonal conditions feed wise for a number of years.

Daytime temperatures in parts have been above average with for example, Tumbarumba average daytime maximum being 2.3 degrees above the average. Some general comments have been that the season is 3–4 weeks ahead than a normal year.

A relatively dry July has prevented the country becoming too wet, and as we looked to the sky for some rain in August, it is now delivering. This will allow pasture growth to get moving as the day length increases.

Spring lambing is in full swing, and even though the season is very good, there has still been some cases of pregnancy toxaemia, in ewes in very good condition and with very large twin lambs. One investigation of pregnancy toxaemia also identified lungworm (Dictyocaulus filaria) and moderate levels of gastrointestinal worms in a mob that missed out on a pre-lambing drench.

The early autumn break in March and continuous green feed since has provided ideal conditions for gastrointestinal worms to proliferate. A few worm egg counts (WEC) from last’s year spring lambs have demonstrated some high numbers. Larval cultures have identified black scour worm (Trichostrongylus) and brown stomach worm (Teladorsagia) with one property with a reasonable level of thin- necked intestinal worm (Nematodirus). If you have not done a WEC in last year’s lambs, now would be the time. Looks like continued WEC and strategic drenching will continue to be constant this year for the next few months, if the rain continues.

We haven't had many reports of worms in the west yet.

The rains have just started up again and with it has come some coccidiosis.

Coccidia are usually an issue in young sheep that haven't yet developed immunity. The issue is worse when overstocked or there is water laying on the ground as this allows a build-up of the parasites.

Moving lambs to fresh ground can help fix the problem with veterinary treatments sometimes being necessary. Livestock sometimes get the double whammy of coccidia infection in addition to other diarrhoea-causing issues such as worms or bacterial infection. Talk to a vet if coccidiosis is suspected.

Good pasture and crop growth is also occurring in the west with some milk fever (hypocalcaemia) seen as well as the aforementioned preg. tox. To prevent milk fever, licks containing calcium and magnesium (such as the home-mix lime, salt and magnesium oxide [e.g. Causmag]) should be available to sheep and lambs, particularly those grazing cereal crops such as wedgetail wheat.


South East LLS

Braidwood: Lou Baskind, DV (

At the time of writing, the town of Braidwood has officially received 152 mm of rain for August. Majors Creek, Araluen and Bendoura reported rain events of 250 mm, and Reidsdale and Northangera closer to 350 mm. Daytime temperatures have hit the 15°C mark on a few occasions, and there have been fewer frosts than is typical for this time of the year.

It is likely that worm larvae will have survived on pastures over winter. Worm larvae are comfortable in cool conditions, and can shelter inside faecal pellets and dung pats. So, if stock weren’t moved on to clean pastures, some worm infection is occurring. Are they completing a full life cycle and dangerously ramping up numbers? Probably not yet, but stay alert.

Worm eggs on pasture need warmth to develop to larvae. While temperatures have been approaching what scour worm eggs would like, there is a cold snap predicted. Usually I wouldn’t worry until the start of October here, but there are strong predictions that September minimum temperatures will exceed the mean. We have the moisture, so if it feels warm, think worms!

July was the typical month to drench cattle weaners and move them to a worm-safe pastures, so do this now if you haven’t already. This will help limit the rapid rise of Ostertagia numbers in spring. Monitor closely for signs of worms such as poor growth (ill-thrift) and diarrhoea (scouring).

The best way to get a handle on where worms are at in your sheep is to do a WormTest – a worm egg count. Kits are available from the Braidwood office—while technically “closed” due to COVID, you just need to ring ahead and make a time to collect your kits.

Cattle lice are very prevalent at the moment. They are loving the cool weather and long winter hair coats of the cattle. Treatment is only required if cattle appear distressed or are causing hide damage from rubbing. If lice have laid eggs (nits), two treatments 14–16 days apart may be needed to break the lifecycle.

The soil profile at the Braidwood soil probe is fully saturated, which is looking good for spring pasture growth. Take care with high percentage clover pastures—I have seen a lot of clover bloats in beef cattle in the past few weeks, especially in areas where the clovers are of older varieties.

Lambing, calving and kidding have started. For those that already have young on the ground, take note of weather warnings—cold snaps can kill young animals, especially if accompanied by rain. Cases of hypothermia have been reported to me, and I examined a mob of young steers with shipping fever: pneumonia caused by a “perfect storm” (excuse the pun) of yarding stress, travel and awful weather.

Yass:  Alexandra Stephens, DV (

There have been very few worm egg count (WEC) results to monitor from the DPI lab this month.

A count from the south coast showed a high WEC of 4000 epg due to a predominance of barber’s pole worm. Two counts from sheep on the southern tablelands showed levels at 40 and 0 epg. A larval culture from the southern tablelands showed a moderate proportion (30%) of barber’s pole worms (Haemonchus) in the sample. 

Worm egg count monitoring has probably been low because many sheep in our area currently have excess nutrition, and many ewes are currently lambing. WECs are of most value on mobs of yearling weaners at this time, but very few tests have been done. Some sheep that had last been drenched in February still had worm counts of 0 and another 40 epg. It is very valuable to monitor now, to see if the hoggets do actually need drenching as conditions are wet and muddy—making it less inviting to bring sheep through the yards. It is also important to monitor for higher counts that may indicate the presence of barber’s pole worm in your WECs. If present, it is extremely important to prime long acting MLs with either a white (BZ)/clear (levamisole) combo, levamisole, Startect, Zolvix or closantel. Resistance of barber’s pole worm to MLs and reduced efficacy of long acting closantel is a real issue in our district. Management of barber’s pole early in the spring, just as the weather starts to warm and allow egg hatching, will greatly reduce the build-up of worm numbers and pasture infectivity.


Western LLS

Bourke: Charlotte Cavanagh, DV (,

There have been several WECs submitted by producers across the Western LLS region over the last month, including submissions from Cobar, Balranald, Broken Hill and Louth. A mixed mob of Dorpers were reported to be in great condition by the owner, however they returned the highest WEC this month with an average of 164 epg. Of these, 98% were Trichostrongylus (black scour worm) and the remainder Teladorsagia (brown stomach worm).

This count doesn’t warrant a drench, but producers are advised to keep an eye on stock as the weather warms up, particularly as there is plenty of moisture around, sporadic showers and some good bodies of green feed.

There is still confusion from some producers around the difference between a drench and a vaccine, particularly as some injectables contain both. In the western LLS region, most of which is extensive grazing, producers are always recommended to do a WEC prior to reaching for a drench for intestinal worms.

Stock should be routinely vaccinated, ensuring boosters are up-to-date. A 6-in-1 is recommended for sheep as this will cover for Cheesy Gland, which is a major source of trim at the processors, as reported by recent National Sheep Health Monitoring Project (NSHMP) data.

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