Lice and mites taking bites: ectoparasites on ducks.
Story by Erin Masur, DVM
With their downy feathers and hardy nature, ducks are less vulnerable to lice and mites than chickens. However, duck owners would be remiss to assume we have one less thing to worry about. Ectoparasites — the creepy-crawlies, including lice and mites, that infest skin and feathers — have been documented in waterfowl. Certain risk factors predispose ducks as ectoparasitic targets more so than other water-dwelling birds, but before we discuss those, let’s review basic lice and mite information.
LICE
The type of lice most often found in poultry are chewing lice (Phthiraptera), which damage feather shafts and barbs via ingestion. A bird’s skin offers protection from the elements through cellular layers and special secretions, so when lice cause damage to skin, the bird’s protective capabilities and energy stores are diminished
Inspect every bird when looking for lice, because a flock infestation will usually spare some of them. Lice are off-white, tan, or yellow and the size of a grain of rice. They’re large enough to be visible to the naked eye, often moving rapidly to escape detection. Part feathers down to the skin around the cloaca. You may also see them around the head, neck, or breast.
MITES
Mites are smaller than lice; pinpoint-sized and dark red or black. They inhabit the feather follicle and ingest the host’s blood. Rarely visible on a bird, if you do see mites, they will be in the facial area. Rather than visible evidence, moderate infestations can manifest as weight loss or decreased egg production. With heavy infestations, birds may experience scabby skin, dull or ruffled feathers, anemia, abrasions, or even death.
There are several types of mites, but the red poultry mite (Dermanyssus gallinae) is the most pernicious and has a reputation for nocturnal activity. If you’re on a mission to find ectoparasites on ducks, a close inspection of the coop is your best bet. The red poultry mite spends its days burrowing into cracks and crevices of woodwork, buried under deep litter, and tucked away in corners of coops and runs. If you’re checking your birds for mites in the daylight and the red mite is your culprit, chances are, you’ll miss it. The red mite waits until the birds are well-roosted for the night before coming out of the woodwork for their blood meals. Because of their capability to shelter inside crevices, housing can remain infested for nine months after birds have been removed.
There are several types of mites, but the red poultry mite is the most pernicious and has a reputation for nocturnal behavior.
If your waterfowl don’t cohabitate with gallinaceous poultry, then the northern fowl mite (Ornithonyssus sylviarum) is likely your culprit. It spends its life on the bird, dwelling on the skin around the vent, and can only survive off its host for one month. During heavy infestations, the northern mite may appear on eggs.
Uncommon in waterfowl is the scaly leg mite (Knemidocoptes mutans), which tunnels under the scales of legs. Chronic infestations take years to manifest, eventually resulting in an outbreak when birds are under stress. To catch this mite, inspect the legs of your oldest birds for scales that look raised, thickened, and crusty.
Assess for Risk Factors
Knowing the risk factors that expose your ducks to ectoparasites enables you to employ holistic preventative measures specific to each factor.
Co-housing. The most significant factor is co-housing with chickens. If you’re determined to raise poultry alongside waterfowl, you may want to consider separating their housing quarters.
Moisture. Another powerful preventative measure is maintaining a dry environment. The highest risk of these little bugs sneaking in is when you’ve had a stretch of wet weather, the run’s been impossible to keep dry, and the coops are damp. To keep the ground dry, you can wrap the run until it’s watertight and use moisture-wicking ground substrates. You may consider adding a gutter system, re-grading, and digging French drains. Be careful when adding hardscaping — pavers, cinder blocks, and other abrasive surfaces can cause bumblefoot.
Vermin. Limiting access by rodents and wild birds removes another risk factor. Regularly inspect housing and clear rafters of nests. Patch holes and tunnels keep feedstuff tidy and sealed.
If preventative measures fail and treatment becomes necessary, be prepared to repeat treatments and procedures for extended periods, because these infestations are tenacious and recurring. Treat ectoparasites from multiple fronts: As a bird problem, an environmental problem, and a coop problem; they need to be addressed with simultaneous treatments.
Duck Baths
It may sound counterintuitive, but thoughtfully designed bathing areas will keep the housing environment dry. Ducks should spend most of their daylight hours outside, and optimal bathing features will maximize their time spent outside the house, increase time bathing, and encourage self-grooming. Enabling ducks to preserve their natural hygiene practices is the best defense.
An optimized body of bathing water has enough surface area for all your ducks to use it at once and is deep enough for them to fully submerge themselves. Keep water fresh and clean or the ducks will not use it to fulfill grooming practices. Provide two sources of water: One for drinking that ducks can’t bathe in and one for bathing. They’ll still drink the bathing water, so keep it as clean as you can. These are tall orders for those keeping ducks in freezing climates, but an ounce of prevention is a pound of cure.
Thoughtful Treatments
To treat the birds, you may need a veterinarian to help choose the right product. There are avermectins, permethrins, and spinosads to name a few; however, they all share the same major flaws. Typically, they’re only effective for a short time, so need to be reapplied frequently. This can become costly, and after several reapplications, you may inch closer to toxic dosing or cause natural waterway contamination. To treat the coop, you’ll need some tools, a pressure sprayer, and a timeline.
The late Extension Poultry Specialist at the University of Connecticut, Michael Darre, laid out an aggressive poultry-house cleaning plan in his article “Cleaning and Disinfecting Your Poultry House.” Darre’s steps include dry cleaning, wet cleaning, soaking, washing, rinsing, drying, and disinfecting, along with which products to choose for each step. This plan will give you a strong start, but even with a squeaky-clean, newly disinfected house, you may need to leave it empty. To eliminate the infestation, you may need to empty the house of birds for up to one month in hot, dry weather, or two months in cold, soggy weather.
A Bucket Load of Prevention
Much like for other maladies that afflict poultry, prevention offers more
success than treatment. Making structural upgrades and regularly cleaning
out your coop will add labor to your homestead; however, you’ll find that dealing with repetitive treatments and lengthy disinfection process when a problem has occurred is more arduous. Regularly perform the procedures you need to catch lice and mites red-handed, and address the factors that could put ducks in precarious territory.
Sources
Choi, Chang‐Yong, et al. 31 Oct. 2016. “Chewing Lice of Swan Geese (Anser Cygnoides): New Host-Parasite Associations.” Korean Journal of Parasitology, vol. 54, no. 5, , pp. 685–691, https://doi.org/10.3347/kjp.2016.54.5.685
Darre, Michael. 7 Apr. 2014. “Cleaning and Disinfecting Your Poultry House.” Cornell Small Farms, smallfarms.cornell.edu/2014/04/cleaning-and-disinfecting-your-poultry-house/
Garbarino, Valentina R, et al. 1 June 2013. “Phthiraptera and Acari Collected from 13 Species of Waterfowl from Alabama and Georgia.” Southeastern Naturalist, vol. 12, no. 2. pp. 413–426, https://doi.org/10.1656/058.012.0214. Accessed 29 Dec. 2023.
“Indian Runner Duck Club | External Parasites Which Affect Domestic Waterfowl.” Runnerduck.net, runnerduck.net/parasites.php
“Mites in Pet Ducks.” PoultryDVM, duckdvm.com/condition/mites
Dr. Erin Masur is a livestock veterinarian located in the U.S. northeast with a passion for small ruminant parasitology. On her own farm, she raises sheep, ducks, and children. Keep up with Dr. Masur’s research at EarlyBirdWorm.com, or check out her services at SheepRockVet.com. For more frequent updates, you can find her on social media by searching for Sheep Rock Vet or Fork You Farms.
Originally published in the April/May 2024 issue of Backyard Poultry magazine and regularly vetted for accuracy.
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