Worm Heat Map – August Edition

Worm challenge in Northern NSW/QLD remains moderate through winter, with both the eastern and western zones averaging just above 200 epg. Most samples submitted were below 250 epg, indicating that many producers have been successful in keeping worm burdens under control despite favourable conditions for winter-active worms. Southern Queensland and the eastern side of the New England Tablelands recorded substantially higher counts and are shown in red. High counts at this time of year in this region are often caused by both barbers pole worm or black scour worm.

With temperatures too low for significant barber's pole development, WormBoss guidelines suggest attention should shift toward scour worms, particularly in young sheep and pre-lambing ewes. Monitoring through regular worm egg counts remains important where stock performance is below expectations.

Central NSW continues to show a marked contrast between regions. The eastern zone remains at a similar level to last month, averaging around 300 epg, while the high-rainfall zone remains very high. These results indicate that winter-active scour worms are continuing to cycle where rainfall has supported larval development and survival.

For winter lambing enterprises, WormBoss recommends close monitoring of lambing ewes and their lambs, as scour worms can impact liveweight gain and productivity at relatively low worm burdens. Worm egg count monitoring remains the most reliable guide for treatment decisions. 

Both eastern and western Southern NSW recorded meaningful increases in worm egg counts compared with June, with average counts rising from low levels into the yellow category. Rainfall and increased testing of younger sheep are likely contributing factors. Despite these increases, most individual submissions still remained below 250 epg.

These results reinforce the value of winter monitoring, particularly around lambing and marking. WormBoss guidance highlights the importance of identifying mobs most at risk rather than relying solely on district averages when making treatment decisions

Overall worm challenge across Victoria remains low. South West Victoria and the Wimmera both remain in the green category, while the North East sits marginally above 200 epg. Most submissions across the state were below 250 epg.

Although average burdens remain relatively low, winter rainfall and lambing activity can create favourable conditions for scour worm transmission. Monitoring ewes around marking and maintaining routine worm testing remains consistent with WormBoss recommendations for this period of the year.

The South East recorded a substantial increase in worm challenge compared with June, moving from a low challenge level into the orange category. This increase was supported by a large number of submissions and therefore represents a genuine rise in regional parasite activity. Fleurieu Peninsula remained relatively low.

The increase observed in the South East highlights the importance of maintaining regular worm surveillance during winter. Where worm burdens exceed local treatment thresholds, treatment should be guided by worm egg count results and resistance-management principles.

Western Australia showed contrasting regional trends. The southern region declined significantly from June and has returned to the green category, suggesting lower parasite challenge than earlier in winter. In contrast, the central agricultural region increased into the yellow category and now sits above 250 epg.

Winter rainfall can support continued larval development in both regions, so WormBoss recommends ongoing monitoring rather than relying on seasonal expectations alone when determining risk.

Across much of southern Australia, winter-active scour worms remain the primary concern. Regional averages suggest that parasite challenge is increasing in several higher-rainfall regions, particularly Southern NSW, South-East South Australia and parts of Central NSW. Regular worm egg count monitoring, strategic treatment based on risk, and consideration of drench resistance remain key components of effective worm control programs through late winter and into spring.