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Flystrike

Posted 6/1/2014 7:41pm by Eugene Wyatt.

It happened yesterday, or the day before yesterday, or some time before Dominique saw the dark fleece around the horns of a Saxon Merino ram Sunday afternoon. We don't know exactly when flystrike started but the ram had gotten wet from the recent rains, the wool close to the horns rotted (it happens every year), green bottle flies laid their eggs in the discolored fleece and the eggs hatched into maggots—1000's of them.

The maggots advance at skin level eating and killing as they go—turning the skin hard, the fleece dark and rotting both—inviting more green bottle flies to lay their eggs as decaying organic matter is an attraction. The number of maggots and the area they inhabit enlarges rapidly. It's fatal to the sheep if not treated promptly by the shepherd.

At pasture in the Summer, Saxon Merino sheep flock, i. e. they move as a unit, and if one sees a sheep separated from the group—his head down in a depressed manner—the shepherd looks at him more closely for the telltale evidence of flystrike: flies buzzing around patchs of dark, lifeless fleece usually near the head.

Treating a sheep for flystrike is time consuming: you must catch the sheep and that is not easy in an open field—if you can't catch it, you must take the entire flock to a closed area with a herding dog where the flystruck sheep can be forced into a blind alley of steel panels and be more easily caught. Then using a good pair of hand shears one trims the rotted wool away exposing the maggots—they hate light—and squirm away from the shears. When one has cut away all the affected fleece to the skin level, one pours on a 7% Iodine solution that desiccates the skin and kills the remaining maggots. Finally one treats the flystruck area with a pyrethrin that will keep flies away.

The prognosis is good on this blue ear tag ram—all Saxon Merino sheep born in 2011 were ear tagged blue; I think we used him to breed purebred Saxon ewes last year. Thanks to Dominique, we caught the flystrike in time and after trimming and treatment we returned him to the flock but we'll keep an eye on him until he's more healed.

Flystrike, when wool sheep are run in larger flocks (or mobs) is why they mules sheep in Australia. The Australian sheep farmer may only see his Merinos once a year at shearing. In America with smaller groups of un-mulesed Merinos someone must look at the sheep every day of the year. Dangerous things can happen on the most beautiful days of Summer. 

Summertime Blues, Blue Cheer 1968-1992

Tags: Flystrike