Blow flies in the family, Calliphoridae, which
includes the black blow fly and the northern black blow fly, the green bottle
fly and the secondary screw worm fly, may deposit eggs in wet wool, stained
with urine, feces, sweat, dirt and other fly maggots. The flies are as large or
larger than house flies and may be metallic in color. These fly-strike areas are often in the
crotch area or at wound sites (shearing wounds).
Maggot-infested sheep are restless, stamp their feet and try to bite at the infested area. They may leave the flock in search of a secluded area. Infested animals do not feed properly, and their general condition declines. Death can occur if the maggots cause lesions, and the lesions become infected.
Fleece weight reductions of 5% have been reported for heavily-infested sheep.
Cultural
Soiled fleece should be clipped.
Shear early so the ewe’s wool doesn’t become dirty from the lambing
process, and shear wounds heal before blow flies are present.
Chemical
Insecticides used for other sheep ectoparasites will control maggots and may prevent fly strike. The insecticides are included in the sheep insecticide table at the end of the chapter.
Categories: Livestock insects, Sheep, Goats, Wool maggots
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