Black flies—also called buffalo gnats—are known to swarm in large groups. But, unlike diseases that may come along with tick and mosquito bites, black fly bites are mostly harmless and often heal without medical attention, sometimes in a matter of days.
Even with regular use of flea and tick medication, your dog can still get bitten—but the good news is that these bites are typically no cause for concern.
Black fly bites usually appear on dogs as flat, red splotches that may or may not be outlined. They’re often called a “bullseye” due to the outline, but the entire splotch may sometimes be a completely dark red lump. Black flies tend to bite exposed areas of your pup’s skin like their belly, inner thighs, or ears.
Small flies, like yellow flies and no-see-ums, leave a smaller mark. Larger flies, like black and horse flies, primarily buzz around large farm animals and can sometimes draw blood. Adults are small (~1/16 inch), have a stout, dark-colored, rounded back, broad wings, and short legs with a few hairs on their bodies.
👉 See our helpful bug bite guide for tips on the treatment of different bug bites on dogs.
Black flies live around flowing water like streams and rivers. Here they lay eggs and the larvae attach to rocks before emerging as flying adults.
They’re also commonly found on and near farms or in wooded areas and lowlands. If your dog has been near any of these environments, it’s more likely the bite you’re looking at came from a black fly.
They tend to be most active in humid, wooded regions during the warmer months but can be found year-round in semi-tropical regions.
If the bites don’t improve, look worse after a few days, or your dog won’t stop itching them, call your vet for treatment advice.
Additionally, your dog may have four common allergic reactions after an insect bite or sting. However, only two are considered life-threatening.
🚨If your dog presents with vomiting, diarrhea, seizures, weakness, difficulty breathing, excessive drooling, pale gums, or hives and swelling in areas other than where the bite mark is, consult a vet right away. These can be signs of anaphylaxis and other larger issues that need to be addressed.
Even if a fly bite isn’t life-threatening, it can still bother your dog and affect their quality of life. Scratching and licking irritated, itchy skin will only add to the misery. Here’s the best way to treat these painful bites:
First, you’ll want to start by carefully cleaning the affected area with warm, soapy water. Be gentle, as this area may be sensitive for your dog. If the wound has scabbed over, you may need to lightly press a warm compress on the scab to soften it before cleaning. Then, apply an ointment on the wound for healing. Keep your dog indoors for a bit to ensure it doesn’t get dirty or the ointment doesn’t rub off.
As with any non-food item, please ensure your pet doesn’t ingest any of these treatments through licking or drinking.
If you notice that the bites aren’t getting better or that the affected area is worsening, consult your vet. This could be a sign of a bacterial infection or other skin issue.
🚨 Avoid using calamine lotion on your dog. Too much zinc is toxic to dogs. (Trusted Source)
Since flies are widespread geographically and very active during certain times of the year in some places, it’s not always possible to avoid them. Here are some tricks to keep their bite count to a minimum.
Before you reach for an insect repellent, consider that products containing DEET and other insecticides carry risks. These chemicals are absorbed through your dog’s skin and can be ingested when your pup licks their fur. Similarly, essential oils may pose similar problems, and some — like cinnamon and citrus — are poisonous to dogs and cats.
Here are some of our recommendations for low-toxicity, dog-safe bug sprays that get a thumbs-up from vets:
The best course of action for black fly bites and other insect bites on your dog is to take preventive measures. If you find your pet with a bug bite, know that it’s completely normal and typically won’t cause any serious issues except itchiness.
While they can occur on any part of your dog’s body, black fly bites can typically be found on the underside of the dog as well as the inner parts of your dog’s ears. Oftentimes they’ll present as red circles with a brighter dot in the middle similar to a bullseye. Large welts or other bite marks may be present, some with a bright red circle encompassing the bite. Know that even with a large number of bites, your dog will likely be okay, just uncomfortable.
Flies tend to gravitate towards strong odors, such as fecal matter or dirt, and one way to prevent the prevalence of black flies is to regularly groom your dog with baths and brushing. If your pet plays in your backyard or partakes in outdoor activities regularly, make sure that there is no fecal matter sitting around. Flies tend to lay their eggs there. Always clean up trash and other waste from around your home and yard.
Another handy way to prevent your dog being bitten is to use hanging fly traps or citronella candles inside and outside of your home.
If you have a favorite insect repellent that you like using on yourself, think twice before putting it on your dog. Pets are at risk for neurological and gastrointestinal issues if exposed to DEET, which is commonly used in insect repellents for humans. You can, however, use dog-safe bug sprays.
The red spots and bites should go away in a matter of a few days up to a week, but if the bites are lasting longer, consider consulting with your vet as your pet may be experiencing an allergic reaction.
While severe cases following insect bites are rare, your pet may present with symptoms like loss of appetite, a rash, weakness, or lethargy which could be an infection. More often than not, your pup will be on their way to healing in no time, but rare cases do occur so it’s important to always monitor your furry friend’s health and well-being.
