Worm Heat Map – June Edition

Worm egg counts across the region have fallen to their lowest levels since the heat map has been produced, with an average of 167 epg, reflecting the impact of both dry and cooler seasonal conditions limiting worm development.

Interestingly, cattle WEC averages (187 epg) are now higher than sheep, which may indicate differing grazing pressures or parasite dynamics across species. Within the region, the western zone remains slightly elevated at 210 epg, sitting in the low–moderate challenge range.

With temperatures dropping, the risk profile is shifting. Scour worms (e.g. black scour worm) are more likely to dominate infections at this time of year. Given their lower treatment thresholds and production impacts, particularly in young stock and pre-lambing ewes, larval differentiation is strongly recommended to guide treatment decisions.

Central NSW continues to report persistently high worm burdens, with a notable proportion of samples exceeding 750 epg. Despite seasonal cooling, these elevated counts suggest ongoing pasture contamination and infection pressure.

In the western region, worm challenge remains very low with most counts returning an zero egg count.

As in northern regions, the likely transition away from Barber’s pole worm towards winter-active species is occurring. Ensuring the correct drench choice is critical, particularly as scour worms can significantly reduce liveweight gain and wool production at relatively low burdens.

As predicted following the March rainfall events, southern NSW has experienced a sharp rise in worm burdens, with the eastern zone increasing significantly from 91 epg to 526 epg. This rapid lift reflects the delayed but expected response in larval availability following moisture and favourable pasture conditions.

In the western zone, worm egg counts rose in April and have remained elevated, currently averaging 274 epg. This sustained level suggests ongoing infection pressure, likely driven by continued larval survival on pasture.

These trends reinforce the importance of post-rainfall WEC monitoring, as significant increases in worm challenge can occur within weeks of favourable conditions.

Worm challenge across Victoria remains generally low, although some regional variation is evident.

Western Victoria continues to record very low counts, with an average of 96 epg. In the north-central region, WECs are slightly higher at 202 epg, however, only 10% of samples exceeded 250 epg, indicating that most mobs remain below typical treatment thresholds.

Overall, conditions suggest a low but emerging risk profile, particularly if follow-up rainfall supports further larval development.

Worm egg counts across South Australia remain relatively stable and low–moderate.

The south-east continues to sit around 210 epg, maintaining a consistent level of challenge over the past three months. On the Fleurieu Peninsula, counts have increased to 251 epg, representing the highest level recorded in this region over the same period.

While overall risk remains moderate, these increases suggest that conditions are becoming more favourable for worm survival, and monitoring should continue, particularly in higher rainfall zones.

Following a decline through the late summer period, worm egg counts have rebounded in May, particularly in southern regions.

Average WEC has increased to 445 epg, with 30% of samples exceeding 500 epg, indicating a return to moderate–high challenge levels. This rise suggests that conditions have once again become favourable for larval development and survival.

Given this upward trend, producers should consider increased monitoring and timely intervention, particularly where production impacts may already be occurring.

In the low rainfall regions of Tasmania, worm egg counts have declined significantly from the elevated levels observed earlier in the year.

The region is now sitting in the green category, with an average WEC of 189 epg, indicating a low parasite challenge. This reduction reflects the impact of drier conditions limiting larval development.

Despite the current low risk, continued surveillance is recommended, particularly following any future rainfall events.