Back to State Outlooks

New South Wales worms, flies and lice update - March 2021

NSW WormBoss Worm Control Programs

NSW WormBoss Drench Decision Guides






Central West LLS

Condobolin: Georgia Grimmond, DV ( and Hanna Thomas, DV (

Very few WormTests have been conducted in the Condobolin district recently, but those that have been have shown a high worm burden when producers weren't expecting it. This emphasises the fact of how important WormTests are. Even though the sheep may look fine it is important to conduct a WormTests to ensure that worm burdens are not creeping up.

Late pregnancy and lambing leads to lowered immune system of ewes and hence a heavier worm burden can occur as a result. This is why monitoring ewes pre-lambing and giving a pre-lambing drench when necessary is essential.

Coonabarabran: Kate Atkinson, DV (

It is a good idea to continue to conduct your worm tests every 4–6 weeks while wet, mild weather persists. We are still seeing mixed barber’s pole and black scour worm infestations.

Drench testing results performed over the summer have generally indicated resistance to single actives such as abamectin, moxidectin, white drenches and closantel. At the moment, we are recommending (in the absence of a DrenchTest that gives more specific drench selection to your property) to use a combination drench with at least three actives or one with the newer actives such as monepantel  plus abamectin (Zolvix Plus™) or derquantel plus abamectin (Startect™). A worm egg count 10–14 days following drenching will indicate whether the drench was effective or not.

If you haven’t already, plan your lambing and weaning paddocks now. The preparation period involves preventing any further contamination with worm eggs from sheep, goats or alpacas in the 3 to 6 months before intended use (3 months through summer, 6 in winter) to reduce the paddock worm burden by 95% and be considered ‘clean’ in most cases.

Dubbo: Sarah Maher, DV (

Worms continue to be an issue around the Dubbo region. Larval cultures are continuing to show not only high barber’s pole burdens but also high percentages of black scour worm, even in areas we commonly see barber’s pole being the main issue. As such producers are encouraged to get a larval culture performed so they know what worms they are dealing with as drench choice may differ with the worm type.

In the last two weeks we have run 12 animal health workshops discussing chemical resistance in flies and worms and how producers can manage that on their farm (pictured right).

With the change of season and rain over the weekend producers should be starting to plan their autumn worm egg count (WEC) with larval culture on representative mobs (we encourage producers to perform a WEC with larval culture three weeks after the change in season hits). In between seasonal cultures producers can do bulk WECs with their local vet or rural merch store to monitor worm burdens.

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

Worm burdens are affecting young sheep across the Forbes district, and larval cultures are showing that while barber's pole is present as expected, all worm populations are present and having a production effect. It is recommended that producers run WormTests on all young mobs of sheep to establish what level of burden is currently present, and determine whether a drench is necessary. If a drench is required, make a careful choice on which product to use — use a highly effective drench product to remove all of the large burdens of worms, with the multi-active (combination drench) products an ideal choice. â€‹Conducting a DrenchTest afterward will also enable you to monitor efficacy of the chemicals used. Withholding periods and Export Slaughter Intervals of the products used will need to be considered for trade lambs.

WormTests should also be conducted before lambing starts for autumn lambing flocks.

Nyngan: Kelly Wood, DV (

Barber’s pole worm continues to thrive in the Central West resulting in substantial production losses and mortalities in the Nyngan district. Animals with compromised immune systems are at the greatest risk of heavy burdens, especially weaners and those undergoing significant stressors, such as lambing for ewes and joining for rams. However, I have recently seen cases of dry/early pregnant ewes dying from barber’s pole worm, highlighting how important it is in a season like this to monitor worm burdens closely. Worm egg count (WEC) testing representative mobs every 4–6 weeks and drenching based on WEC thresholds described in the WormBoss Drench Decision Guide is the safest way to manage worms on your property and mitigate the risk of drench resistance.

Consistent, effective worm management will help prevent extremely large worm burdens developing on pasture which can then be difficult to “clean up” for use during lambing and weaning. Given the mild summer we have had, which will have allowed increased larval survival on pasture, we are urging producers to consider techniques for reducing larval burdens in addition to paddock spelling (or using significantly elongated paddock spelling times) when preparing pastures for high-risk mobs. Cropping, mixed or rotational grazing and smart grazing can all be used to decrease the number of larvae on pasture — details on how best to implement these tools can be found at the WormBoss website.

Effective worm control relies on appropriate drench selection which in turn relies on knowing what species of worms you are dealing with and what drench resistance profiles are present on your property. Selecting a WormTest Gold (with larval culture) is important as we have seen much higher black scour worm burdens in the district this summer than we have in recent years, likely reflecting the milder season. We are also urging producers to plan to conduct a drench resistance trial on their property with this year’s weaners. Central West district vets have ten different drenches available for testing and will run the program with producers only having to pay for the WormTests. If you are interested, please contact your local district vet for more information.

Heidi McGrath, Charles Sturt University
Heidi McGrath, Charles Sturt University

Murray LLS

Albury: Mark Corrigan, DV ( with Heidi McGrath, Charles Sturt University

Over the last month of February, Albury and surrounds has seen a total of 55.4 mm of rain, slightly about the 25-year average for the area, with temperatures ranging from 15.3-27.8 degrees Celsius. With our summer rains and warmer weather, we have also seen an increase in ground cover and perfect conditions east of the Hume highway for the three main worms that affect sheep and goats to rise; black scour worm (Trichostrongylus spp), brown stomach worm (Teladorsagia circumcincta) and barber’s pole worm (Haemonchus contortus).

Locally we have not seen a huge rise in barber’s pole worm, most likely due to proactive farmers staying on top of worming and inspecting their stock for classic clinical signs including bottle jaw. We have seen a moderate rise in other strongyle counts (mainly black scour worm and brown stomach worm) across the NSW Murray Region, with average counts reaching 284 eggs per gram (epg). Worm counts should be interpreted based on the type (age, reproductive status, species) of stock, clinical signs and condition of the animals. This sort of count in heavily pregnant stock could warrant a drench. Worm management strategies, including type of drench can be found on the WormBoss website or discussed with your local veterinarian.

With the late spring extending into summer rain and increase in fresh feed available, we have also seen an increase in worm egg counts in cattle.

The usefulness of worm egg counts (WECs) in cattle can be limited compared with sheep and goats, however, they are more reliable in young cattle under 18 months of age. Recently we have seen a case where yearling heifers had a count of over 600 epg. Worming had occurred last spring, but due to good summer rains, green feed and a mild summer some increase in worm numbers has occurred on this property. Therefore it would be worthwhile to do some WECs on your young stock if you are in an area that has had good summer rain.

In adult cattle the number of eggs produced by worms can be lower. This means a high WEC is significant; however, cattle can be suffering from worms even when WECs are low. Blood testing to assess pepsinogen levels can be used in conjunction with WECs, helping to provide an indication of abomasal (fourth stomach) damage which can be due to brown stomach worm and possibly barber’s pole worm.

Cattle are most affected by worms in the 3–6 months after weaning (i.e. in autumn for spring-born calves), with adult cattle generally developing good immunity to worms. Calves should be drenched at weaning and turned out onto clean, rested pastures. In liver fluke prone areas, blood testing can be carried out on cattle in the late summer and autumn (often done at preg testing) to help give an indication of liver fluke exposure. April–May can be considered a critical liver fluke drench period.

In cattle, sheep and goats, a DrenchCheck is a great way to ensure that your drench is doing its job. It is recommended to first take individual or a herd faecal sample and send it away for a WEC, worm your stock and then take another sample for a WEC in 10–14 days post-drenching to ensure the worming is working adequately.

For March 2021 state outlooks, please follow the links below:
Back to State Outlooks