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Queensland worms, flies and lice update - March 2019

Brisbane: Maxine Murphy, Veterinary Parasitologist (maxine@paraboss.com.au)

Most sheep areas have remained hot and dry and are still severely drought affected. There have been a few storms across the region, but most were patchy and didn’t amount to much.

Barber’s pole worm burdens usually peak in March although the peak this year is likely to be significantly reduced due to the searing temperatures (above 35°C) and dry conditions over the summer. Worm eggs and larvae on pastures are surely dead. However, there are always surprises, especially in sheep that are poor doers. Sheep on poor feed for an extended period become malnourished, and even a few worms can exacerbate a chronic issue and be a reason to drench.

Worm Tests are advised to monitor for worm build-up that often occurs if stock are crowded in feedlots or on areas of green pick. They can provide a good measure of the average worm burden of the mob which may, in fact, be low, but poor doing animals may have quite elevated worm egg counts, which will be shown by doing individual worm egg counts.

If worm egg counts in the mob or individual animals are more than 100 eggs per gram 10–14 days after drenching, then drench resistance will be the most likely cause. Effective combination drenches are recommended as a routine.

Autumn is the time to prepare for lambing. Decisions need to be made on how to achieve a low worm pasture and what would be an effective drench for the lambing ewes. Paddocks take about 3 months in summer and 6 months in winter to become sufficiently free of larvae to be considered low-worm and suitable for lambing.

During March and early April sheep should be monitored for flystrike.