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Control of ectoparasites in dairy herds

Nuisance flies

Flies can cause irritation, stress and seriously affect cattle productivity. The main months for fly problems are May-August, but due to changing weather patterns the season can change. The most common species that affect dairy productivity are:

  • Non biting flies – house flies and face flies – these flies do not bite, but they breed easily in manure, quickly forming large numbers which can cause great irritation and transmit diseases. Animals that are distracted by flies will graze less and hence not perform as well.
  • Biting flies – horse flies and stable flies – these flies deliver extremely painful bites, with both males and females feeding on blood. Horn Flies are blood sucking flies and are extremely irritating and can cause production losses.


Lice are mainly a problem with housed cows in the winter and can reduce dairy productivity. Symptoms include itching, hair loss, hide damage and anaemia (sucking lice).

There are sucking and biting lice:

  • Sucking lice pierce the skin and suck the blood and can cause anaemia. They tend to be found around the head and neck of cattle.
  • Biting lice feed on skin debris, blood and scabs. They tend to be found on the neck, shoulders, back and rump.


Mange mites cause irritation, thickened scaly skin, hair loss, hide damage and reduced dairy productivity. These are mainly a problem in autumn, winter and early spring.

Different mites are commonly found in different body areas as follows:

  • Surface mites – neck, legs and tail head, causing areas of hair loss which increases in size and causes irritation.
  • Burrowing mites – neck and loin area next to the tail, producing intense irritation and severe skin damage. Large areas become thick, crusted and eventually infected.
  • Psoroptic mange – back, shoulders and tail head causing severe dermatitis, scabs and intense itching.