Towards a practical trap for deer flies (Diptera: Tabanidae): initial tests of a bi-level Nzi trap

Abstract

A modified Nzi trap was tested at a residence and at a farm in eastern Ontario, Canada to better capture high-flying tabanids (Diptera) such as Chrysops Meigen. A new upper trap entrance was created to provide a higher and larger opening by reducing the front blue top shelf to half its height. To minimise escape of low-flying tabanids, a vertical inner baffle was added to direct low-flying tabanids up into the cone. Half of the tests of 18 new designs caught 1.5-2.7 times more deer flies than the Nzi trap did, with the other trap designs being as effective as the Nzi trap. The optimal design that maintained equal catches of other biting flies relative to the Nzi trap was one with a phthalogen inner horizontal shelf and a netting inner vertical baffle. This design is defined in the present as the bi-level Nzi trap. Chrysops entered the trap mostly through the top (88%; 17 spp.), along with Hybomitra Enderlein (94%; 12 spp.). Tabanus Linnaeus (9 spp.) entered through both entrances. The most abundant Tabanus, T. quinquevittatus Wiedemann, entered mostly through the bottom (70%), whereas Stomoxys calcitrans Linnaeus entered mostly through the top (92%).