Whether out for a jaunt in the woods or just trying to enjoy a backyard barbecue, black flies can be a pesky problem when you are outside. Also referred to as buffalo or turkey gnats, there are over 250 kinds of black flies in North America alone and over 2,000 different species worldwide. Some areas, like New England, hold over 50 species per state. Black flies require fresh, usually running water to breed. Some species are found exclusively in large, fast-flowing rivers, whereas others prefer slow-moving rivulets.

Black flies typically mate in the late spring or early summer, depending on the latitude. Like mosquitoes, only female black flies bite as they require blood to fertilize their eggs and will suck blood from virtually any warm-blooded creature they can find. Some species spend the winter in the egg stage, remaining submerged and hatching when water temperatures warm to 40- or 50-degrees Fahrenheit in the spring. The larvae then develop during the early spring and emerge as adults in late spring or early summer. Many black-fly species produce more than one generation each year.

If the pests feed on the blood of an animal carrying parasites, black flies can transmit diseases during feeding. While black flies do not carry the same or as many of the diseases mosquitoes do, black fly bites are painful and can cause illness and even death in some cases. In some regions, black flies carry river blindness and black-fly fever.

River blindness is caused by infection of the microscopic parasitic Onchocerca volvulus worm. Symptoms typically include bumps under the skin, severe itching, and blindness. While it is the second-most common cause of blindness due to infection, it is not as common in North America as black-fly fever after trachoma. Black-fly fever symptoms include headaches, fever, nausea, and swollen lymph nodes, and symptoms may be exacerbated by an allergic reaction that may require medical attention.

While there are some non-biting black fly species, these can be just as annoying as they like to target the eyes, ears, nose, and mouth, and these species can cause symptomatic toxic shock if one is accidentally swallowed. The best course of action is to keep away from black flies or, in the alternative, keep them away from you with a good bug spray or black fly repellent. Here are some proven ways to ward off black flies:

1) Natural Scents
Drinking an ounce of apple cider vinegar is reported to have many medicinal properties and causes you to give off an odor the flies do not like but humans cannot detect. Vanilla extract, pine, or lavender oil repels biting black flies and mosquitoes too. Herbs like anise, basil, cedarwood, coriander, lemongrass, and mint may work to repel black flies and can be planted in flower boxes or pots and around the edges of your yard. Garlic plants are also reported to have a repelling effect.

ward off black flies

2) Commercial Repellents
The natural scents are worth a try, but they probably won’t be effective on all species of black flies. If this turns out to be the case, there are plenty of very effective commercial repellents available. While insect repellents with DEET are incredibly effective at deterring black flies, many people are concerned about using harsh chemicals. DEET has been reported to cause skin and eye irritations, confusion, slurred speech, and seizures. There are bug sprays on the market that are highly effective and do not contain harsh ingredients. Picaridin bug repellent based on an ingredient found in the pepper plant works to keep pests away. For those with dry or sensitive skin, a good insect repellent lotion will also help moisturize while protecting you from bugs.

3) Clothing
Scientific studies have shown that bugs are attracted to darker colors, so wearing a light-colored shirt, pants, and a hat will help keep black flies and other flying bugs from targeting you. Wearing light colors also makes it easy to spot any bugs that end up on you. Also, be sure to wear long pants and a long-sleeved shirt rather than shorts, and a t-shirt as these make it harder for bugs to bite you through the fabric. Additionally, zippered garments will keep black flies out better than buttons. In areas with heavy black fly infestations, wear a bug net over your face to keep the little bugger away from your nose and mouth as black flies are attracted to the CO2 you exhale.

4) Avoid using Attractants
As black flies are attracted to sweet smells and CO2, avoid using products with strong fragrances like perfume, aftershave, soap, shampoo, and hair spray. If possible, try to keep from overexerting yourself, as it will cause you to breathe heavier and produce more CO2.

5) Smoke
Like most bugs, black flies hate smoke, and staying close to a burning fire will keep most pests at bay.

6) Fans
Black flies are not strong fliers, so they cannot fly well in strong winds. Because they are so lightweight, a few strong fans placed strategically around your yard will keep black flies away. Large box style and outdoor fans will work best for this type of application.

7) Avoid Black-Fly Habitat
Black flies are typically found in areas of dense vegetation and will swarm in sheltered and shaded areas with high moisture. These places include lakes and pond inlets as well as streams and rivers. This is because fungi grow in these areas where black flies like to lay their eggs. It is best to avoid these places if at all possible during their breeding season. It is good practice to always carry travel-size bug spray with you if you unexpectedly venture into a black-fly habitat.

8) Avoid Peak Activity
Like most insects, black flies are most active during dawn and dusk when the temperature and winds are down, and the humidity is high. Activity tends to peak between 9:00 to 11:00 AM and 4:00 to 7:00 PM. Of the two time periods, the evening sees the most activity. If you have to venture into their domain, wait until midday when the wind is up or after dark as black flies do not bite at night.

9) Treating Black-Fly Bites
While it can take a few days to heal, a black fly bite is easily treated in the following ways:

  • Wash the area with soap and warm water.
  • Apply aloe vera gel, witch hazel, calamine lotion, or other gentle topical agents to reduce irritation.
  • Use an antihistamine lotion if symptoms of an allergic reaction occur.
  • Do not scratch the bite area or it can become further irritated and infected.

Following these steps will help ward off black flies when venturing into the woods or just enjoying your backyard. Remember, the best advice is to stay out of areas of prime black-fly habit whenever possible, be sure to cover up at peak time during the breeding season, and always wear a good bug repellent. PROVEN makes an effective picaridin-based black fly repellent as part of their bug spray line of products that can be purchased online at provenrepellent.com or in stores.

ward off black flies