Superb Dog
black fly biting

Black Fly Bites on Dogs – How Dangerous Are They?

Black fly bites can look serious and make your dog uncomfortable, but they are usually harmless unless they get infected.

Black fly bites are very common in the warmer months, especially around areas with large bodies of water. It’s not unusual to see both humans and dogs alike getting bitten. Black fly bites can look quite serious, and how dangerous are they to dogs?

Black fly bites may look bad but ultimately pose a low risk to your dog. They can possibly lead to infections which can have serious consequences, but by carefully monitoring your dog for symptoms after noticing black fly bites, you can reduce the risk of serious damage to almost zero.

We’ll look at what black flies are, what their bites look like, and what you can expect to happen with a bite from black flies. We’ll also consider some treatment and prevention ideas to help mitigate any damage from black fly bites as best as possible.

What Are Black Flies?

Black flies are very commonly seen flies, especially visible in the warmer months. Sometimes known as buffalo gnats, they feed off of blood from animals and don’t particularly know or care where they get it from.

Black flies are the ones you see in the air during summer and spring, flying around and annoying people (and animals). On their own they don’t amount to much; they’re so small and their lifespans are short that they’re unlikely to pose a large issue.

However, black flies tend to produce large amounts of young and they will gather in swarms, meaning that a single annoying fly can very quickly turn into many thousands of very annoying flies.

They tend to lay their eggs in water, and it doesn’t have to be still water either. Black flies will happily lay their brood in moving water, meaning if you’re near a body of water, this can be a huge source of black flies.

Black flies, like almost all insects, do bite but these are not particularly poisonous or an issue. Large swarms of flies, all biting, can cause some issues, leaving behind itchy spots.

On their own, the bites are not much and are quite unlikely to cause significant issues. The complications arise when the bites become infected or do not heal properly.

What Do Black Fly Bites Look Like?

Black fly bites have a distinctive look that can be spotted even amongst all that dog hair.

Generally, black fly bites will be a vivid pink or red ring around the bite, with a central red dot. It often is mistaken for a tick bite, which is confusing as there will generally be no evidence of a tick.

It’s important to realize that tick bites manifest completely differently in humans and dogs; dogs generally suffer lameness in their legs as opposed to the bull’s eye red mark that accompanies human lyme disease.

Most black fly bites are flat with a raised center. These bites tend to be itchy, causing your dog to constantly scratch the area. Of course, the more numerous the bites and the larger their actual size, the stronger urge to scratch.

This urge is an effect intended by the black fly. Natural selection has found out that the skin is a very tough barrier to get past. One way to do so, is to create an urge to scratch or rub an area of skin by the host, in this case the dog, in order to break the skin barrier.

This allows the bacteria and other nasties to get in, causing infections and further issues from an otherwise innocuous bite.

It’s actually the fly’s saliva that causes the itchiness, as it causes an immune response from the organism it’s getting the blood from.

The common areas to find black fly bites are in vulnerable or soft parts of the skin. Think about the unprotected parts of a dog’s body that may prevent a black fly biting, such as hairless areas on their belly, thighs, and ears.

dog itches black fly bite

Are Black Fly Bites Dangerous?

On their own, you don’t have much to worry about from a black fly bite, or even several. The same goes for your dog. What you should be on the look out for is the secondary infections that can develop from these bites.

Secondary infections have some common hallmarks that you should look out for before the condition becomes an illness. Swelling and discomfort around the bite mark as well as a gradual worsening of your dog’s color are the early signs of infection.

Other signs of a developing infection or related illness include shortness of breath, swelling, hives or rashes, diarrhea and difficulty moving or walking.

This also means treating these bites is relatively straightforward. Usual topical ointments and mild solutions containing a weak soap will help keep the wounds clean and moisturized. Ice packs will also help reduce swelling.

Just as we do treat bites on ourselves, applying Neosporin Antibiotic Ointment or Polysporin (a similar antibiotic topical which doesn’t contain neomycin, which some dogs are allergic to) can help with black fly bites among many other applications. They both contain bacitracin and zinc to provide infection protection. Of course, alway check with your vet before treating medical issues yourself.

In very rare cases, your dog may have an anaphylactic shock or allergic reaction to a black fly bite. This of course needs a visit to the vet as soon as possible.

You can expect most black fly bites to clear up after a week or so. Most dogs are not even going to notice or care about these bites. You may notice increased licking or scratching of the problem areas.

How Should I Reduce the Danger From Black Flies?

A great way to prevent black fly bite complications is to use insect spray. There are specially-made dog insect repellents that can go a long way towards preventing black fly bites before they happen.

Flys-Off Insect Repellent for dogs is safe for dogs and will not only prevent black flies but also gnats, mosquitoes, fleas, ticks and even lice.

Of course, prevention is the best cure, so if you notice a swarm of black flies developing, get indoors.

Rain or storms as well as bodies of water will bring the black flies out, so again plan any trips accordingly.

The common meme of garbage attracting flies is something to take note of. Try to keep garbage levels to a minimum by always disposing properly through sealing your bags and putting in garbage cans with properly sealing lids.

Dog defecation also attracts black flies, so be sure to pick up your dog’s poop immediately (you should be doing this anyway for a number of reasons!).

A great tip is to put the topical ointment on the black fly bite and then take your dog for a walk. As the walk acts to distract the dog, they’re much less likely to lick it off and reduce its effectiveness.

Another way to lower the chance of your dog getting bitten is to put an old t-shirt on them. This may not be ideal for summer months, but it does provide a barrier that can make black fly bites less likely.


Black fly bites by themselves are mostly a nuisance and generally don’t present any risk to your dog. However, if the bites get infected, the usual risks that accompany infection come into play and you should quickly address them with your vet. Also, making sure that the irritations are actually black fly bites and not another type of bite or rash is important to avoid misdiagnosis.

Superb Dog Editor

Superb Dog Editor