Greenheads – You Can Set Your Calendar By Them

Greenheads are in the genus Tabanus and are one of a few families of biting flies. They get their greenhead name from their large eyes which are brilliant green in color and their bad reputation from their distinctive and painful bite.

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Greenheads are a Plague
The problem – as if there is only one – is that greenheads all emerge the first week of July in New England the larvae pupate and emerge as a plague of biting flies. In their adult form, greenheads are short lived. They only survive for four-six weeks before they die. That’s a huge amount of pressure for the females to mate and lay their eggs. That pressure gets a little worse and the rest of us literally feel their pain.

You see, one of the many other problems with greenheads is that the female must have a feast of warm blood to complete her reproductive cycle. Her bite and your blood are necessary in order for her to successfully lay the eggs that will become next years plague of greenhead biting flies. Doesn’t it make you feel better knowing that despite the bite and the pain, your blood is fueling the next generation of greenheads?

Set Your Calendar by Greenhead Time
Like Fireworks on the Fourth of July, they always emerge at the same time. Not long after we spring forward and a while before we fall back, there is greenhead time. It is a black mark on the calendar and might win-out over Halloween as a time when fear strikes the heart of people and animals alike in greenhead territory.

The bigger problem when greenheads emerge is that they do so over a very short span of time. The air literally becomes a biting zone for those 4 to 6 weeks over which all the greenheads mature.

These are not small Flies
Greenheads are big usually .75 inches in length. They are fast, strong fliers too. Their bite literally leaves a mark and can cause scarring if it becomes itchy or infected. If bitten by a greenhead you will have no problem knowing it. It’s a painful bite and designed to produce plenty of blood. The female can ingest as much as one CC of blood per bite. She injects a little anti-clotting serum so that your blood flows freely. To get your blood to flow freely she plunges into your flesh two scissor-like mandibles which fly open like a rusty pair of garden shears. As they do, they sever many small capillaries which give her a quick meal and cause a bloody mess. All the anti-clotting serum not only burns like the dickens but just keeps the blood flowing.

To paint a better picture of why greenhead season is a problem, understand that each female lays between 100-200 eggs and that most of them hatch and emerge at the same time. For that 4 to 6  week span, areas around marshes, the beach, and farms become a living hell.

We mentioned that greenheads are strong fliers and they do not have a problem covering a huge territory. It is sort of a “you can run, but not hide” scenario. They will head to the beach looking for prey and fly inland to hit the towns and ranches looking for blood.

So, come the first week of July, you might as well just take a permanent marker pen and line out the next 6 weeks as Greenhead time (GHT.) Your only chance of avoiding greenheads is to stay indoors or you can use the Fly Cage which attracts greenheads and then destroys them.