Blackfly Infestation

calendar icon 22 March 2019
clock icon 2 minute read


Grey-black hump-backed flies, 5 mm long and found in North and South America that are external parasites of birds and mammals. The flies transmit leucocytozoonosis and also a filarial parasite in ducks. The condition tends to occur near to rapidly flowing streams, although these insects can travel up to 15 miles. Eggs and larvae survive through the winter to cause new infestations in the following year.


  • Anaemia in young birds.
  • Swarms of flies.

Post-mortem lesions

  • Anaemia.


Anaemia, season, local history.


Treatment is difficult.


Similar measures as for mosquito control. Biological control using a strain of Bacillus thuringensis has had some success and is preferable to insecticides. Weekly treatments are required.

Extracted From:
A Pocket Guide to Poultry Health and Disease by Paul McMullin© 2004

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