Greenhead Fly Traps

Like everyone else around here, we’ve outfitted our greenhead fly trap (above) with re-purposed packaging

On the rare occasions that we go away for the weekend, the place we usually go is to the marshlands of south Jersey on the Delaware bay. Reed’s Beach is a nature preserve and a critical stopover for migratory birds en route to arctic breeding grounds. (See Nature.org)

Because it’s a nature preserve, it cannot be developed any further. The houses on stilts and the trailers that were already there can stay, but no new construction is permitted.

For bird watchers this place is some kind of Mecca, and for a few weeks in May while the horseshoe crabs are spawning and the red knots & ruddy turnstones are feeding—(although not so much now as in the past)—the beach is closed to humans.

One regrettable feature of life in Reed’s Beach and similar wetlands communities, are the greenhead flies.

Adult flies mate on the open marsh. Within a few days and without seeking a blood meal, the female lays her first egg mass, consisting of 100 to 200 eggs. To produce additional egg masses, the female needs a blood meal...

Adult female greenheads move from the salt marsh to nearby wooded or open areas along the marsh edge to seek suitable blood sources. There they await and attack wildlife, livestock, and people that venture close enough for them to detect.

Females live for three to four weeks in the uplands before they become too weak to bite. Because of this long life, larger numbers of blood hungry flies build up in areas near salt marshes. The physical removal of large numbers of flies can reduce this buildup and thus decrease the greenhead fly problem locally.

The Greenhead and You
Elton Hansens and Stuart Race, Rutgers University

It was Elton Hansens and Stuart Race (quoted above) who designed the greenhead fly trap that we use. The original plans (below) call for a dark black box, open at the bottom with screen at the top into which a couple of hole with cone shapes guide the flies to the top —(they naturally tend to fly upwards towards-the-light)—where they are invariably imprisoned in packaging.

The original instructions mentions using “transparent shoe boxes” but as a DIY necessity, individuals here will use will just use whatever packaging is at hand: bottles, jars, takeout food containers, etc. One innovation that everyone seems to be onboard with: the neck of a PVC bottle makes a good cone and is easier than fashioning a cone from screening, as the original design stipulated.

(See some more examples, after the fold...)

Randy Ludacer
Beach Packaging Design

Comments

[Graz]

Thanks for getting back to me Randy.

Building one (or a few) of these will definitely be this weeks project. I'm not sure if you're familiar with the Jersey Shore, but my family recently got a home in Barnegat, and it's very beautiful. The only thing that sucks about it, are the greenhead flies!

I see that one of the traps pictured is utilizing a black painted milk gallon (or some other type of bottle) as a lure. Do you find that the use of the lure captures more flies than the traps without the lure?

THANKS for all of your help!

[Randy Ludacer]

Hi Graz, Thanks for commenting.

If you're in an area where greenhead flies are biting, these traps are definitely worthwhile. Even one hungry & persistent greenhead fly can make a person pretty miserable. Capturing that one fly spares you those bites. And our trap has taken quite a few greenhead flies out of circulation.

[Graz]

I was thinking of making one of these traps. Do you know if they work well? Are they worth it?

Thanks for the pictures as well. They'll be very helpful if I decide to build this!