Building a Better Fly Trap: Day Campers Conduct Science Experiment

Recently, some very strange objects suddenly appeared in the day camp field at the head of the Bay View Trail.

Other worldly-looking things which appeared in the field!

These space alien-looking contraptions were installed by our day camp’s Ecologists group  with the help of property manager James Nielsen for a scientific experiment.

The objects are called H-Traps  for biting flies, including the dreaded greenhead fly that terrorizes beachgoers during mid-summer.


One of the experiment’s targets: the greenhead fly, denizen of the salt marsh.

These new traps include a large round black plastic sphere, a cone-shaped plastic sleeve that hangs above it, with a plastic collection bin at the top.

Without any lures, these odd-looking contraptions are able to attract greenheads, horseflies and other biting flies in the Tabanidae family and trap them. But how??

First, we should note that the biting flies are all females looking for blood to produce eggs. They typically find a good supply in large animals–such as people and horses. Both prey species give off two things that attract the flies– warmth and carbon dioxide. The black spheres absorb the sun’s warmth and emit fly-attracting heat.

The black sphere looks and feels like an exercise ball.

James demonstrated installing the first trap. Then it was up to the Ecologists to do the rest:

Connecting the green funnel with the metal holder which will attach to the frame.

The trap design is based on a second fly factoid: After the female bites, she typically flies off vertically–straight up. If she does this from the black sphere, she’ll find herself inside the green funnel and eventually in the collection bin at the top.

James helped the campers with the first one but the kids installed the final two on their own within minutes.

As with most projects, our day camp crew made quick work of installing the traps. And it didn’t take more than a couple of minutes to achieve their first catch:

Our first “customer”–a deer fly, a greenhead relative. Pretty cool!

And in less than two hours, the collection bins on all three traps had flies. Amazingly, just 5 days later, all three traps had caught a combined total of nearly 1200 flies! And this was without any lures.

But the next step is to introduce two different types of lures (the ingredients of which have been found safe by the EPA) to assess which attracts flies better.

The campers will learn to use the scientific method, follow experimental protocols, and collect and maintain the data that will be turned over to the fly trap manufacturer after the summer.

The first week’s data sheets from the field and vials containing nearly 1200 biting flies.


Our thanks to Robert Bedoukian, a distinguished scientist and entrepreneur, who reached out to Wellfleet Bay to provide a meaningful research opportunity to day campers. Robert and his wife Gail, from Connecticut  and Eastham, donated all the material needed and will work with staff during the two month study while they await the results of the research.


8 thoughts on “Building a Better Fly Trap: Day Campers Conduct Science Experiment

    1. Wellfleet Bay Post author

      Hi, Dan,

      The flies are counted, either by hand or by a method the kids came up with the speed up the counting given the fact they’re catching so many. They record which trap using which bait caught the flies. The bait is being rotated amongst the three traps, with one trap always being unbaited, as a control. The basic scientific method they’re learning plus the labor intensive field work gives them a real flavor for what research is all about!

        1. Wellfleet Bay Post author

          Hi, Dan,

          Yes, they are. The idea is to reduce the number of greenhead flies — which enjoy wide abundance and distribution– in a very limited area–such as someone’s backyard

    2. Wellfleet Bay Post author

      Yes, they are. Greenheads are abundant and widely distributed. The trap is designed to reduce their numbers in a very localized area, such as a backyard. The traps are amazingly specific at the insects they attract and capture– all members of the tabanidae family (biting flies).

  1. Gail Bedoukian

    Hi, Robert and I love the blog and hope you will continue giving reports!
    I would like to write a news story on the Bite-Lite website and was hoping to get more information, such as: how many campers are involved in the science experiment, how long does the camp go and campers participate in the h-Trap experiment, what are the ages of the campers running the experiment, how long did it take to put up all three traps, will just the Explorers program be involved or will other campers from different programs be involved, can you give me an update every time you do you a rotation, and any other information that would be interesting.

    1. Wellfleet Bay Post author

      Hi, Gail,

      We’d be happy to keep you posted. Our science coordinator Mark Faherty is overseeing the project. I plan to do a follow-up blog post on this and as I gather info I can pass it along to you. Or you can get in touch with Mark directly, give him some questions by email that he can respond to when he has the info. I can supply photos. The kids and staff are really enjoying this project! Mark can be reached at [email protected] Thank you! Jenette Kerr


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