Baffled by Marsh Structures?

Fly Boxes Keep Beach-goers Comfortable

By Laura Hedges

Hampton Union, Tuesday, August 11, 2009

[The following article is courtesy of the Hampton Union and Seacoast Online.]

HAMPTON -- For those who have stared at those strategically placed boxes sitting on poles in the salt marshes and wondered, "What the heck are those?" we suggest you blend yourself a margarita and find a comfortable spot in the sun, because the answer to your burning inquiry is about to be unveiled.

These seemingly benign structures on Hampton town property are the key to a beach visitor's relaxing day on the sand. They are the antidote to pain and an environmentally-sound solution to protecting all warm-blooded mammals.

These boxes trap those vicious green-heads, a form of deerfly.

According to Dragon Mosquito Control's Sarah McGregor of North Hampton, insects such as mosquitoes, horseflies and deerflies are on the rise this season. Because of the heavy rains, an ideal mud nest in salt marshes has been created and is providing the perfect breeding ground for a variety of insects.

McGregor said that the Hampton salt marshes are home to deerflies, in particular, which are a smaller species to horseflies, but can be just as bothersome.

According to the University of Florida Agriculture of Food and Sciences department, deerflies inflict deep wounds using the mandibles to penetrate the skin in a scissor-like fashion. That may cause a flow of blood.

Anticoagulants in the fly's saliva are pumped into the wound to allow the blood to be ingested.

The department says disease producing pathogens may be transmitted from flies as they feed on first one animal and then on another.

McGregor said catching their attention as they first hatch is the best way to trap the flies. She said that while working in insect control, she has found that people who use similar traps on their lawns usually don't have much luck catching the biting flies because grassy areas are not the habitats that they breed in.

The insects are attracted to large, dark objects and as they approach the boxes in the salt marsh, they believe they are approaching a warm-blooded meal. Drawn to the bottom of the box, the flies are suctioned into a funnel where they eventually die of dehydration.

According to the University of Florida Agriculture of Food and Sciences department, spraying marshes for deerflies is not a feasible option because it would difficult to pinpoint the area most likely to be the breeding ground and the pesticides used could threaten the important ecosystem.

McGregor said that the traps are commonly mistaken for devices relating to research on bird habitation because some researchers use similar structures for those purposes. Although this is not their primary purpose, when McGregor empties the boxes she said she will often find mice skeletons left there by predatory bird.

As far as these traps impacting the food chain, McGregor said that salt marshes are widespread across New England and picking off a few flies with these traps would not amount to a loss of nutrients to birds and animals dependent on them for food.

"Deerflies are having a good season," said McGregor. "They're pretty much like fast food for other animals."