ARS | Publication request: Performance of the Nzi and Other Traps for Biting Flies in North America

Submitted to: Bulletin of Entomological Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 16, 2006
Publication Date: May 16, 2006
Citation: Mihok, S., Carlson, D.A., Krafsur, E.S., Foil, L.D. 2006. Performance of the nzi and other traps for biting flies in north america. Bulletin of Entomological Research. 96:1-11.

Interpretive Summary: Nzi traps are blue-colored cloth traps designed to capture biting flies by using visual attractant properties without using baits or electrical power. The traps were originally made of African blue cotton to catch large numbers of African tsetse flies, and the same traps were found to be very effective in North America as well. A scientist at the CMAVE laboratory in Gainesville, Florida worked together with the major developer of the Nzi trap to define the range of colors, materials and effectiveness for several trap types in the USA and Canada. They found that just one excellent material was available, an acrylic fabric awning material called Sunbrella that was colored with a bright blue pigment called phthalogen blue. Several cooperators participated in field tests, and found that blue Sunbrella was the most effective trap material for catching both horseflies and stable flies in North America. The copper-containing color is very stable, does not fade even after many months of sun exposure, and can be obtained when mixed in commercial paint to paint wooden traps. We believe that these results provide the design for a practical, robust, long-lasting trap that will effectively capture biting flies near cattle and horses for more than one year.

Technical Abstract: The performance of Nzi traps for various biting flies and mosquitoes was investigated in a residential setting in Ontario, and in natural or artificial settings in Alberta, Florida, Iowa and Louisiana. Selected fabrics, insect nettings, dyes and paints were compared to standards from the original African design to provide recommendations for North America. Comparisons of substituted materials showed that optimal trap performance occurs only with the deep, brilliant blues produced by the pigment copper phthalocyanine (phthalogen blue), or its sulphonated forms (turquoise). Other blue chromophores were not attractive (anthraquinone, triphenodioxazine, indanthrone, disazo, formazan). Appearance as opposed to color was also critical. Smooth, shiny synthetic fabrics (polyester, nylon) or blends with cotton reduced catches, as did shiny paints. Lower catches relative to phthalogen blue cotton occurred even for specialty fabrics in widespread use for attracting tsetse in Africa. The use of a specific type of insect netting or screening was less critical to trap performance; white mosquito netting was however the optimum material for all groups. The only readily-available fabric in a suitable blue was Sunbrella acrylic awning/marine fabric. It met conditions of durability and attractiveness, and had a matching colour-fast black. A convenient option for North American consumers, painted plywood, was also investigated. Painted plywood traps with white mosquito netting performed as well as cloth traps, so long as tint formulations dominated by copper phthalocyanine were used.