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Tropical Fowl Mite Infestation

Other Names: Bird Mites

The tropical fowl mite, Ornithonyssus bursa is a common ectoparasite of chickens and wild nesting birds (such as pigeons, starlings, and sparrows) living in subtropical and tropical regions worldwide. It looks very similar to the Northern fowl mite.

Clinical Signs of Tropical Fowl Mites in Chickens

Tropical fowl mites cause irritation (excessive itching), painful dermatitis, feather loss, and anemia in chickens. The mites are most commonly found in the vent area and accumulate in masses on just a few feathers.
Signs of tropical fowl mites in chickens
Tropical fowl mites can also spread from the birds to humans---resulting in avian mite dermatitis (also referred to as gamasoidosis or acariasis), characterized by prolonged itching, welts, and painful dermatitis.

The tropical fowl mite is known for inhabiting abandoned nests of wild nesting birds. They may also become a pest to humans in areas of high bird populations or where wild birds are allowed to roost on roofs and around the eaves of homes. The life cycle of the tropical fowl mite is similar to that of the Northern fowl mite. It lays its eggs on the birds or in the nests, which take 3 days to hatch. They will almost immediately begin feeding off the blood of the birds and increase in their numbers rapidly. Without a blood meal from a bird host, they usually will die within 3 weeks.

Clinical Signs

Blackened vent feathers (which is caused by an accumulation of fowl mite feces, dead mites, and dried blood)
Feather loss near vent area
Irritation, excessive itching
Pale comb/wattles
Hens not laying eggs in nestboxes
Mites crawling on eggs


  • History
  • Clinical signs
  • Physical exam

Reported Cases

  • Case 1: Tropical fowl mites in a Chickens A total of 70,000 commercial laying hens housed in a raised platform system with 17,500 birds in each shed was severely infested with mites. The infested birds showed signs of restlessness, pale comb and wattles, intense scratching, and decreased egg laying. Ref


SulfurApplied as a dust directly on the chickens, added to their dustbathing area or hanging small gauze bags of sulfur dust around the premises.A Murillo et al., 2016
FipronilSpray the base of the neck, tail base, and under each wing and repeat in 30 daysB Speer; Clinical Veterinary Advisor
Spinosad (Trade name Elector PSP)Applied as a spray on all coop housing components.B Mullens et al., 2017; A Murillo et al., 2017; Dow AgroSciences 2001
Fluralaner (trade name Exzolt)Added to the flock's drinking water. The product is administered twice, 7 days apart so it treats two mite life cycles. There is no egg withdrawal period and trials show it to be 99% effective at killing mites.N Hinkle, et al 2018; A Prohaczik et al., 2017; B Mullens et al., 2017
Ivermectin0.2 mg/kg PO, SC, IM, topical once and repeated in 10-14 days.B Speer; W Campbell et al., 1984; S Lee et al., 2006
Garlic spray10% garlic solution diluted with water, sprayed on the chicken's vent and abdomen, once every 7 days for 3 weeks.Birrenkott, G. P., et al., 2000
Diatomaceous Earth (DE) (food grade)Apply by dusting onto the chicken's feathers or added to their dust bathing area. Also dust all housing components. Replace bedding and nesting material.A Murillo et al., 2016; C Martin et al., 2012; D Bennett et al., 2011
MalathionUsed as a spray or powder applied to all housing components in coop.G Damerow
PermethrinApplied as a powder (0.24% permethrin) or spray (3 ounces of 10% permethrin is mixed in a 5 gallon bucket of water), directly on the chickens as well as all housing components. Replace bedding and nesting material.G Damerow
Thyme essential oilApplied as a spray directly on the mitesT Smith et al., 2017; F Masoumi et al., 2016; D George et al., 2010; IS Nechita et al., 2015; A.M Quilicot et al., 2020
Hemp essential oilApplied as a spray directly on the mitesMA Tabari et al., 2020
Ajowan essential oilApplied as a spray directly on the mitesAI Baran et al., 2020
Garlic extract or essential oils10% garlic solution diluted with water, sprayed on the chicken's vent and abdomen, once every 7 days for 3 weeks.Birrenkott, G. P., et al., 2000; A.M Quilicot et al., 2020
Syzygium aromaticum essential oilApplied as a spray directly on the mites.MA Tabari et al., 2020



  • Remove abandoned wild bird nests which are located near where your flock lives.
  • Discharge wild birds from nesting in, on, or in the vicinity of coops.
  • Periodically remove and replace any materials present in nestboxes and all bedding materials (hay, straw, shavings, etc).
  • Discourage wild birds by removing bird feeders and bird baths.
  • Control rodent populations, as they can sometimes be carriers of mites and ticks.
  • Thoroughly clean any branches, wood stumps, or other tree-sourced items containing bark.

Scientific References

Risk Factors

  • High populations of wild birds nesting in the area.
  • Abandoned wild bird nests
  • Not regularly (at least once a month) changing materials used for nestboxes.
  • Adding tree stumps or branches to your run before cleaning them first.
  • High rodent populations.