Black Fly Bites on Dogs: Identification, Treatment, and Prevention

Home remedies and preventive tips to help your pup stay itch-free all season long.

By Medha deb

Created on Aug 29, 2025

Home remedies and preventive tips to help your pup stay itch-free all season long.

As the warmer months approach, black fliesâalso known as buffalo gnatsâbecome a nuisance in many regions. While their bites are uncomfortable for humans, they can also affect our canine companions. Knowing how to identify black fly bites on dogs, provide appropriate treatment, recognize when veterinary intervention is needed, and prevent future bites can help keep your pet comfortable and healthy throughout the fly season.

What Are Black Flies?

Black flies are small, blood-feeding insects commonly found around bodies of water, forests, and shaded wooded areas during late spring and summer. Unlike mosquitoes, black flies are most active during the day and tend to attack in swarms. Their bites are notable for causing noticeable skin reactions in both humans and animals.

Identifying Black Fly Bites on Dogs

Recognizing a black fly bite on your dog is the first step toward effective care. Although the marks may resemble other insect bites or even bacterial infections, some features are unique to black fly bites.

Appearance: Black fly bites often manifest as bright red, flat welts that may have a classic “bullseye” or target-like appearance. The center can be pale with a red ring, or the entire welt may be dark red in color.
Location: Bites are most commonly found on thinly haired or exposed areas such as the underside of the belly, groin, inner thighs, flanks, ears, and muzzle.
Lesion Size: Lesions range from the size of a pea to a nickel.
Behavior: Dogs may show little to no discomfort, though some scratch or lick the area, increasing the risk of infection.

It’s important to distinguish these marks from those caused by ticks (which can transmit Lyme disease in humans) or other parasites and skin infections. When in doubt, consult your veterinarian for a proper diagnosis.

Symptoms of Black Fly Bites in Dogs

Most black fly bites cause only mild, localized symptoms. However, it is crucial to observe your dog carefully, as some pets may develop more extensive reactions.

Localized Redness: Red spots or welts, occasionally with bruising or bleeding beneath the surface.
Mild Swelling: Particularly at the bite site.
Itching or Irritation: Dogs may lick, chew, or scratch at the affected areas.
Rare Allergic Reactions: Hives, swelling in other body parts, facial swelling, excessive drooling, vomiting, diarrhea, or collapse may indicate a severe (anaphylactic) response and require immediate veterinary attention.

Why Do Black Flies Bite Dogs?

Black flies are attracted to warm-blooded mammals, particularly during the day, and are drawn to exposed skin. Dogs with thinner coats or those who spend time in shaded, wooded, or wet environments are most at risk. The bites occur as black flies make small cuts in the skin to feed on blood, which can result in irritation and inflammation.

Treating Black Fly Bites on Dogs

Most black fly bites are self-limiting and resolve within several days. However, some basic home care steps can help alleviate your dog’s discomfort and prevent further complications.

Keep the Area Clean: Gently cleanse the affected area with cool, mild soapy water to remove bacteria and prevent infection.
Apply Cold Compresses: Use an ice pack or cold, damp cloth for 5â10 minutes to reduce swelling and soothe irritation.
Use Topical Creams: Hydrocortisone creams or aloe vera gel can be applied to reduce inflammation and itching. Ensure your dog does not lick the treatment; use an e-collar or cover the area with a light t-shirt if necessary.
Antihistamines: If your dog shows signs of significant itching or mild allergy, your veterinarian may recommend an antihistamine like diphenhydramine (Benadryl). Only use medications in the dosage prescribed by your vet.
Prevent Licking and Scratching: Dogs that persistently lick or scratch the area can cause secondary infections. Use an Elizabethan collar (e-collar), an old T-shirt, or another barrier as recommended by your vet.

If any sites become increasingly swollen, red, or begin to ooze pus, contact your veterinarian. Infections may require prescribed topical or oral antibiotics.

Symptom	Initial Home Care	When to Call Vet
Red, flat welts	Clean skin, cold compress	Persist after a week, spread, or seem infected
Itching/licking	Monitor, use e-collar or clothing, cream	No improvement, skin breaks open, infection risk
Swelling or hives	Antihistamine if prescribed	Severe swelling, difficulty breathing, vomiting
Signs of infection	Gentle cleansing, topical antibiotic	Pus, persistent swelling, systemic illness

When to Consult a Veterinarian

Most cases of black fly bites in dogs do not require veterinary attention. The following scenarios, however, warrant a professional consultation:

Multiple bites or extensive irritationâespecially on sensitive skin.
Signs of infection, such as pus, excessive swelling, or discharge.
Allergic reactions, as evidenced by widespread hives, swelling of face or limbs, vomiting, diarrhea, difficulty breathing, or collapse.
Lesions that persist beyond a week or worsen over time.

Your veterinarian may prescribe antibiotics, stronger anti-itch or anti-inflammatory medications, and provide specific instructions for ongoing care. In rare cases of anaphylaxis (a life-threatening allergic response), emergency intervention with injectables and supportive care is crucial.

Prevention: Reducing Black Fly Exposure and Bites

Prevention is the best way to keep your dog comfortable during black fly season. While no method is foolproof, the following strategies can significantly reduce risk:

Avoid peak fly activity: Black flies are most active during daytime, particularly in late spring and early summer. Schedule outdoor walks or playtime outside these hours when possible.
Minimize time near water: Limit your dog’s exposure to areas near rivers, lakes, or marshlandsâespecially during fly season.
Protect vulnerable skin: Dress your dog in a light T-shirt to cover the underbelly and inner thighs where fur is sparse.
Yard management: Keep your yard well-maintained and use pet-safe insect repellents as recommended by your veterinarian.
Use screens or netting: If your dog must be outside for long periods, consider using a screened kennel or mesh netting to provide a physical barrier to flies.

Black Fly Bites vs. Other Insect Bites

Understanding the differences between black fly bites and bites from other common insects can help guide appropriate action:

Ticks: Often attach to the skin and can transmit diseases; may leave a red mark but not a classic bullseye on dogs.
Mosquitoes: Usually cause smaller, itchier raised bumps with less dramatic redness.
Fleas: Bites produce tiny red spots, often clustered on lower back, belly, or hindquarters.
Bees/Wasps: Can leave stingers and cause more pronounced swelling; removal and monitoring for allergy are essential.

Seek veterinary assessment if you are unsure which insect caused your dog’s symptoms, or if their condition worsens.

Possible Complications

Though rare, black fly bites can lead to complications, particularly if your dog has a hypersensitivity to insect bites or if they cause secondary skin infection by excessive licking or scratching. Watch for the following:

Worsening redness, swelling, or spreading rash.
Open sores, lesions, or pus discharge.
General unwellness (listlessness, reduced appetite, fever).
Symptoms of systemic allergic reactions, as outlined above.

Always err on the side of caution and consult your veterinarian if any severe symptoms arise.

Frequently Asked Questions (FAQs)

What do black fly bites look like on dogs?

They usually appear as round, flat, bright red marksâsometimes with a target or bullseye appearanceâon exposed areas such as the underbelly, groin, or ears.

Are black fly bites dangerous for dogs?

For most dogs, black fly bites are harmless and resolve on their own. Serious complications are rare but can include allergic reactions or infection from excessive licking or scratching.

How can I treat black fly bites at home?

Clean the area with mild soap and water, use cold compresses, and apply veterinarian-approved topical creams. Prevent your dog from licking or scratching the site. Contact your vet if there is swelling, pus, or if your dog acts ill.

When should I take my dog to the vet?

See your vet if the bite area becomes infected, your dog develops extensive swelling or hives, experiences breathing difficulties, or if symptoms persist beyond a week.

Can I prevent black fly bites?

While black fly exposure can be reduced by avoiding peak activity and covering vulnerable skin, no method is 100% effective. Monitoring your dog and using protective measures is key during black fly season.

Key Takeaway for Dog Owners

Although black fly bites on dogs may look alarming, most heal without intervention. Understanding the signs, basic care, and when to seek veterinary help ensures your dog stays healthy and comfortable. Always consult your veterinarian with concerns or for personalized adviceâespecially if your dog has a history of hypersensitivity to insect bites.

References

Author

medha deb

Medha Deb is an editor with a master's degree in Applied Linguistics from the University of Hyderabad. She believes that her qualification has helped her develop a deep understanding of language and its application in various contexts.

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