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Blackflies: Don’t let flying jaws ruin your spring

  • Simulium trifasciatum, also known as a black fly. John Curtis’s British Entomology



For the Monitor
Friday, May 04, 2018

Piranhas of the air. New Hampshire’s state bird. Buffalo gnats.

They go by many names but mostly we call them: black flies.

These tiny insects, which have begun to emerge, are enough to make even avid nature lovers, like myself, want to retreat inside for a few weeks. But wildflowers are blooming, gardens need to be planted and migrating song birds are beckoning as they fill the air with music, so we must endure the flying menaces or miss out on many spring specialties.

Since all organisms have a role to play in the environment, let’s start by answering the question: “What good are black flies anyway?”

As an insect that spends its larval stage in running water, they can send a message about the quality of the rivers in which they live. The larvae produce silk threads to attach themselves to rocks, vegetation or other submerged substrate. From this position they extend fan-like brushes into the current, filtering and cleaning the water as they feed on algae, bacteria and microorganisms. They are also sensitive to pollution, so their presence indicates a healthy ecosystem.

When the adults hatch and take flight, they become important food for fish, amphibians, birds and other insects such as dragonflies. Some migratory song birds carefully time their return to coincide with the abundant food provided by emerging black flies. Erecting bird houses for species such as tree swallows can encourage this natural predation and benefit both you and the birds.

Another way to look at black flies is to be grateful for the things they are not. Of the 40 species that live in New Hampshire, only two are significant human biters. The species emerge at successive times during the spring but their combined season is only for about four to six weeks. The best thing is that the species which inhabit New England are not vectors of any disease that is harmful to humans. The worst thing that we get from a black fly is an itchy bite. Some people may be more sensitive to the bite than others, but severe allergic reactions are extremely rare.

A black fly bite is always administered by a female because she needs blood to lay her eggs. Both male and female black flies feed on nectar for general metabolism. The female uses her file-like mandible to cut and abrade the skin. An anticoagulant in her saliva causes blood to flow which she then laps with her tongue. This is very different from the piercing and sucking action of mosquitoes, and also accounts for the longer recovery required from a black fly bite, because it is more of a wound to the skin.

There are many ways to prepare yourself for black fly season so you don’t have to sequester yourself indoors for six weeks.

Avoid being out during their prime times of early morning, just after sunset, and right before a storm. They also seem to prefer cloudy and humid weather.

They are most common in wooded and sheltered areas so plan to spend more time in open places.

Take advantage of breezy times which tend to keep them at bay.

Cover as much skin as you can and wear light colored clothing.

Tuck your pant legs into your socks and wear sleeves with cuffs to keep them away from your ankles and wrists.

Donning a head net will keep them from your eyes, ears and neck, and give you a distinctive outdoorsy look!

Avoid using any perfume, aftershave or fragrant soaps and lotions.

Some people claim that eating raw garlic keeps them away.

Many hardcore New Englanders have their favorite treatment including a long list of bug repellents which range from strong chemicals to more human- and environmentally-friendly herbal and essential oil mixtures. Everyone has their preference and effectiveness varies with body chemistry and diet so, experiment and determine what works best for you.

The main trick is to arm yourself with a positive attitude and whatever else you need to stand up to this temporary nuisance. The black flies may keep the tourists away but they shouldn’t keep you from enjoying the all too brief bit of spring that we have in New Hampshire.