The pipes carry carbon dioxide and octenol, a chemical that sand flies mistake for water buffalo breath, which they relish. To evaluate how deadly the fence is, Day places traps inside the fence on the playground. The playground traps consistently have a lower sand fly count. Day also turns the fence off periodically to do bite counts, which always go up when the fence is not operating. Day said he hopes for a long-term impact on the overall sand fly population after the fence has been running for months or even years.
Sand flies infest all of coastal Florida.
The carbon dioxide fence grew out of a 14-year research project to develop environmentally friendly techniques of trapping sand flies. Mineral oil works beautifully because it is non-toxic and the sand flies are not strong enough to fly out of it. Historically, we'd treat a marsh like this one near the school with DDT, and that worked great. Later, we'd treat it with chlordane, and that worked great. Besides, if you spray all the vegetation on the edge of the marsh with insecticide, you kill every insect that lands on that vegetation, not just sand flies.