Sudden Death in Backyard Poultry – Consider Black Flies

By Dr. Cindy Bell

Earlier this spring of 2018, the death of a bull and cow in Arkansas was linked to black flies of the insect family Simuliidae¹. In a more recent article dated May 25, 2018, news from Iowa linked high mortality in backyard poultry flocks with black flies². Some species may feed preferentially on birds, Simulium flies bite and feed on a wide range of mammalian and avian hosts, including many species of livestock and humans. Simulium meridionale, also known as the “Turkey gnat,” has been linked to an outbreak of acute avian deaths in Louisiana in 2010, which affected pet birds and poultry³. This particular species is prevalent throughout the Mississippi valley and its distribution extends west into Kansas. In the Louisiana outbreak, sudden deaths occurred even psitticine birds that had been kept in outdoor aviaries.

Death associated with black flies is usually peracute or acute, occurring within 24 hours in cases of severe swarming. Sudden death may be the only problem noted. When swarmed by black flies, birds may exhibit lethargy, anorexia, ruffled feathers, and petechial hemorrhages on skin. Anemia may or may not be a feature.

Based on the life cycle of these flies, which breed only once during the year, the threat in Kansas for 2018 has likely passed as temperatures have soared and large swarms of adult black flies that emerged this spring have already started to die back. In Southern states, black flies are most severe in the spring and die back by early summer. In Northern states, late spring and early summer can be the peak time.

Barriers (e.g. screens) and mechanical control (fans, fly strips) may be sufficient to protect poultry and other livestock from morbidity and mortality associated with black flies. These methods are often safer than chemical insecticides and are uncomplicated by regulations. Historically, carbaryl (also known as Sevin dust) was used widely in poultry for control of arthropod pests and parasites. Permethrin products are recommended since they are generally safer and not as strictly regulated as carbaryl. (Please note, permethrin is highly toxic to cats!)

References and resources:

Black flies – USA (Arkansas): Livestock deaths, ProMED mail, International Society for Infectious Diseases, http://www.promedmail.org/post/5732701
Fly bites causing chicken deaths in central Iowa, Ames Tribune, http://www.amestrib.com/news/20180525/fly-bites-causing-chicken-deaths-in-central-iowa
Avian Simuliotoxicosis: Outbreak in Louisiana Author(s): Rodney W. Schnellbacher, Kali Holder, Tim Morgan, Lane Foil, Hugues Beaufrère, Javier Nevarez, and Thomas N. Tully, Jr. Source: Avian Diseases, 2012; 56(3):616-620.
Hall RD, Gerhardt RR. Flies (Diptera) in Medical and Veterinary Entomology, Mullen GR, Durden LA, Mullen G. eds. 2002, Elsevier Science & Technology, p. 127-146.
Pesticides used for control of poultry insect pests, Mississippi State University Extension, http://extension.msstate.edu/content/pesticides-used-for-control-poultry-insect-pests

If you have questions, please contact KSVDL Client Care at 866-512-5650 or clientcare@vet.k-state.edu.

Exotic Tick Found in the U.S.
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