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

NSW WormBoss Worm Control Programs

NSW WormBoss Drench Decision Guides






Central West LLS

Coonabarabran: Kate Atkinson, DV (

Barber’s pole worm remains a problem in the region with spring weather. Some drench trials have been conducted in the region in the past month with some initial results showing barber’s pole resistance to macrocyclic lactones (eg. moxidectin, abamectin). In some farms there was also levamisole and closantel resistance when these chemicals were used as the sole drench. Benzimidazoles (albendazole etc) have widespread resistance when used on their own. Results are farm-specific and cannot always be extrapolated to the wider region. It is recommended that landholders have a strategic drench plan in place that incorporates worm egg counts (etc) and drench resistance testing and checking in order to delay, reduce and manage resistance problems.

Restocking can also be a source of drench resistant worms. Be sure to quarantine drench any newcomers onto the place with a combination drench of at least 4 different classes of drench including a newer drench such as monepantel (Zolvix™) or derquantel (Startect™). Quarantine for 1–3 days to empty out eggs then release new sheep onto a ‘dirty’ paddock from homebred sheep to dilute any resistant eggs.

Coonamble: Jillian Kelly, DV (

The warm temperatures and the regular showers of rain have seen barber’s pole worm burdens around the Coonamble district explode. To give you an example, two WormTests from around the Gulargabone area this week measured 4,500 and 6,000 eggs per gram. We have performed two DrenchTests over the last month — they show worrying levels of drench resistance. Farm 1 had resistance to levamisole, white/clear combos, moxidectin and a triple active product. This farm is going to have to manage their barber’s pole worm burdens carefully this summer, using the newer active ingredients such as monepantel and derquantel when going onto clean pastures as well as closantel with tail cutters when using dirty paddocks. Farm 2 had resistance to closantel, the mectins and closantel/mectin combination. This farm has very few long acting drench options available to them, and so are going to have to consider careful pasture management to reduce larval burdens, and potentially use of novel approaches to barber’s pole worm such as Barbervax™ in coming years. We are encouraging all farms to do a DrenchTest to assess their unique drench resistance profile. We are also encouraging farmers to do a WormTest, drench strategically after getting some good advice about drench selection, and to not forget about the sheep and their worm (and fly!) burdens over harvest.

Dubbo: Sarah Maher, DV (

Conditions around the Dubbo area are perfect for worm survival; in the last month we have seen quite a few WormTests with strongyle counts, well over a 1,000 eggs per gram. We are encouraging producers to conduct a WormTest before they drench. WormTests should be performed three weeks after a break in weather or rainfall event, as it takes approximately three weeks from larvae being consumed and the sheep producing eggs.

Producers are also encouraged to start thinking about what paddocks they will use next year and how they will prepare clean paddocks over summer.

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

With harvest rapidly approaching, local producers are encouraged to take action to prepare sheep for the current conditions to avert any problems during this really busy time. Recently weaned lambs should have been given an effective drench at weaning and placed into a clean paddock. Make sure this paddock is not a risk for grass seed infestation, as young sheep can suffer very badly in paddocks heavily contaminated with grass seed! For other sheep, use WormTests to monitor worm burdens and assist you in making the best drench decisions. We have not investigated any cases this season where worms have been an issue, but are certainly on the lookout, particular for barber's pole worm. This worm thrives in these spring conditions, and as the female lays a huge number of eggs each day (around 10,000) and so outbreaks can be explosive. The larvae are blood feeders, and can cause an affected sheep to become anaemic very quickly. Anaemia causes weakness and lethargy,  lagging behind during mustering, and potentially death. Bottle jaw, a fluid-type swelling under the jaw is another classic sign. Fly control is also imperative in spring. FlyBoss has some excellent tools to assist you with planning and prevention. 

Nyngan: Kelly Wood, DV (

With harvest probably getting underway for most producers before the next ParaBoss update, now is the time to get a parasite plan in place so that you don’t have a disaster on your hands. Although much of the green feed is starting to hay off, there is still sufficient rainfall predicted through the end of spring to allow worm larvae to develop on pasture. You should be worm testing any lambs that will be weaned in the next two weeks and also putting a follow-up WormTest in your calendar 4–6 weeks after drenching your weaners with an effective short-acting product. WormTests on representative mobs of hoggets are also recommended. Testing one in three flocks of similarly aged and managed animals (on comparable pasture with a commensurate drench history) will give you a good idea of how your sheep are travelling and whether you need a strategic drench to get you through harvest. Remember, by the time you are seeing clinical signs of worms in your sheep, you have already lost production. Pale and bottle-jawed sheep are just the tip of a very costly iceberg and often barber’s pole outbreaks will just present as deaths in the paddock.

To get the most out of your WormTest, you need to be collecting fresh dung (both warm and moist) from at least 20 separate piles. This can easily be done by walking around a sheep camp or by holding sheep in the corner of a paddock for 15–20 minutes. Aim for a representative sample, i.e. collecting pellets and soft dung if both are present. Try to collect samples early in the week and to send it the same day that it is collected to prevent the worms from hatching in transit and falsely lowering your egg count. Request a larval culture when there are more than 200 eggs per gram as it provides you with valuable information for drench selection and efficacy, especially in areas where you suspect barber’s pole. However, a larval culture cannot be performed on samples that have been refrigerated so if you have missed the post, collect some fresh samples the following day.

Riverina LLS

Narrandera/Griffith: Sophie Hemley, DV (; and Hay: Georgia Grimmond, DV (

Despite seeing a lot of scouring sheep across the district, scour worms have not often been the cause based on our investigations. Worm egg counts this winter/spring have been reportedly low based on recent lab submissions. Despite this, the lush green feed this year has resulted in a lot of daggy sheep and as a result blowfly activity is well and truly on the rise. Preventing flystrike in sheep generally involves preventing/treating scours thereby controlling dags, crutching or shearing prior to high risk periods for strike, docking at the correct tail length, mulesing where appropriate and applying chemicals that interrupt the lifecycle of flies to provide long-term protection.

Keep in mind that preventing flystrike is far more economical than treating it and increased reliance on chemicals alone will contribute to resistance and start to become a burden on your coffers. The best time to consider using chemical application is at the point of synchronized emergence, whereby the fly pupae (that are dormant within the soil over the cooler months) respond to warming temperatures and mature into adult flies. This will disrupt the life cycle of the fly and help to minimise fly populations. With harvest just around the corner, ideally choose products that will ensure protection of your flocks over harvest. This information is clearly displayed on the product labels or if you need help choosing a product jump onto the FlyBoss website.

If you missed the boat for fly prevention, FlyBoss has some fantastic resources on how to treat flystrike and can help you to develop a fly management plan.

Murray LLS

Albury: Mark Corrigan, DV ( and Eve Hall, DV (; and Deniliquin: Linda Searle, DV (

The season in Murray has continued to progress well with crops now turning and pastures coming to head. Producers have been busily spraying and slashing barley grass to reduce the potential impacts on their livestock, but it looks like a bad year for grass seeds.

In the east there have been a couple of cases of mycoplasma ovis, bacteria that cause red cell destruction leading to anaemia. An outbreak in a flock usually occurs in young sheep 4–6 weeks post mulesing or shearing where the bacteria is spread by infected blood on equipment. In the cases identified the lambs showed signs of weakness as they were mustered to be weaned, and on closer inspection the lambs had pale mucus membranes. Barber’s pole worm, another common cause of anaemia in warm and moist conditions was ruled out by a post mortem examination and finding no evidence of worms in the abomasum. If you are mustering young sheep at this time of year and they show signs of weakness, the first step would be to undertake a worm egg count (WEC) before yarding to prevent the sheep from having to go through a stressful situation that could cause a number of losses. The results should be discussed with your veterinarian before further action is taken.

WECs in the east have predominately identified black scour worm (Trichostrongylus spp) and recently lambs at marking had WEC at over 500 eggs per gram. Continue to monitor WEC and larval culture in a year that will continue to be challenging for good worm control. 

Investigations in the west to issues with farmed goats found high numbers of worm eggs despite recent drenching. While Black scour worm is usually the most abundant worm found in the west these goats were found to have 75% Teladorsagia and only 25% black scour worm. Drench resistance is a common issue in goats. Very few worm drenches are registered for goats, and goats usually need different dose rates and have different withholding periods compared with sheep. Management of worms in goats should be part of an integrated strategy including grazing management, breeding worm resistant goats in combination with strategic drenching. More information can be found via WormBoss.

We are also starting to get some high WECs in the west in sheep. Black scour worm is usually the most abundant worm found although there are increasing numbers of Teladorsagia. While barber’s pole worm is usually less of an issue it has been identified recently in sheep in the Berrigan area.

South East LLS

Braidwood: Lou Baskind, DV (

Rain has fallen over the last few months lifting much of the South East region out of drought. Even some of our most intensely drought-affected areas are starting to recover. At the time of writing, the town of Braidwood has received 58.4 mm of rain in October, bringing Braidwood’s total for the year to 719.8 mm. It’s almost certain that the whole South East region will receive enough moisture over the next month to continue to support worm development. While the Snowy Mountains remain cool, the rest of the South East is now in a temperature range that promotes worm eggs hatching and developing to infective larvae. The sheep worm to watch for now is barber’s pole, that becomes active at slightly warmer conditions than the other roundworms.

As a result of these wet and warm conditions, many properties are experiencing superb pasture growth. This has two benefits when it comes to worms: firstly, worm larvae can only move to about 5 cm up the pasture sward, so when stock graze taller pasture they will pick up less larvae; secondly, good nutrition from quality pasture promotes the development of immunity to worms. But not everyone has been as fortunate – the impact of drought and bushfires means that not all pastures have been able to spring away. Worm monitoring and control should be an even higher priority if livestock are grazing short pastures.

Cattle are monitored for internal parasites by close observation of their performance. Sheep should be monitored by using a worm egg count or WormTest, that simply requires the collection of fresh dung. As part of a bushfire recovery fund, properties in the South East that were bushfire affected or in proximity to the summer bushfires may be eligible for a free WormTest. Contact South East LLS for more information. If you have never done a WormTest this might be a fantastic opportunity to give one a go and see the benefits for yourself! Your district vet can guide you through the process from start to finish.

Weaning of lambs is coming up soon and a chemical drench for lambs at weaning is recommended. Lambs are very susceptible to worms and effective drenching will help them to survive the stressful weaning process. Many drenches are now available in smaller packs, making drenching of small numbers of animals much more practical. Using combination drenches is important to slow the development of resistance to the chemicals. For most drenching, using a combination of effective drenches is by far the best way of slowing resistance, rotation has little impact except as the next drench after use of a long acting product or after using a prepared low worm-risk paddock. Drench resistance could leave you with few options to manage worms on your property.

Finally, a quick note about another parasite — a parasite of plants this time, but one that is having major animal health effects — the cowpea aphid. The Monaro region is experiencing a significant infestation of cowpea aphids on lucerne pastures. The aphid is not only damaging the lucerne but is causing a syndrome of photosensitisation in sheep. Photosensitisation is a very painful condition resulting from toxins accumulating in the skin and reacting to UV light. You can read more about it in the latest press release.

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