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Western Australia worms, flies and lice update - May 2015

WA WormBoss Worm Control Programs

WA WormBoss Drench Decision Guides


Albany: Brown Besier, DAFWA (brown.besier@agric.wa.gov.au)

Sheep worms:

The pasture situation across the state is variable, depending on how well recent rains have kept the earlier germination going, but conditions now are close to ideal for worm development on the ground. Providing there is some green feed, there will be enough moisture to allow worm eggs to develop to the larval stage, and with temperatures still in the low 20s on some days, larval numbers will build up from now on.

Whether there is any significant risk to grazing sheep depends on how many worm eggs they are putting out. The advice for WA in the last couple of ParaBoss newsletters was to ensure that worm egg counts were low in all sheep by mid-autumn, ahead of good conditions for worm development. Sheep carrying significant worm burdens may be setting up a worm problem in winter or spring.

Action: If not done in recent weeks, worm egg counts should be checked in weaners and hoggets in the next 3–4 weeks, as invisible burdens may be reducing growth rates, as well as putting a lot of worm eggs onto the pasture.

For ewes due to lamb in the next month or so, there should be no need for a pre-lambing drench if the recommended autumn drench was given with an effective drench type. However, if no autumn drench was given, or there is a query over how effective it may have been, worm egg counts should be measured so treatment can be given before lambing starts, if needed. A maximum of 150 eggs per gram should be allowed at this time, ideally under 100 eggs per gram.

A barber’s pole worm warning: the early pasture growth in coastal areas has increased the risk of this unwelcome visitor. The main concern is in ewes due to lamb in June: if no drench was given, say less than 6 weeks before lambing, worm egg counts should be done. If there is a high barber’s pole level, the long-acting drench closantel may be advised, to give peace of mind against disease outbreaks while the ewes are lambing.

Blowfly strike?

We’ve heard of a few cases of strikes recently along the south coast, following significant rainfall and relatively warm temperatures. Fly activity will reduce as it gets cooler, but it will be worth keeping an eye out for the next couple of weeks.