Attractants for the Walnut Husk Fly1

Abstract

The initial and continuing effectiveness of a sticky trap baited with powdered ammonium carbonate as an attractant for the walnut husk fly, Rhagoletis completa Cresson, was studied in comparison with that of a standard glycine-sodium hydroxide bait solution. The characteristics of the ammonium carbonate trap were determined for the purpose of optimum use in surveys of the distribution of this species, for which this trap proved to be well suited. Among other ammonia-producing salts studied was diammonium azelate, which was initially more effective than ammonium carbonate but declined rapidly. Diammonium succinate was only slightly less effective than ammonium carbonate. Of other types of dry traps baited with ammonium carbonate, a sticky trap consisting of a waxed and plastic-lined cardboard tube hung horizontally proved to be twice as effective as the standard sticky trap. A plastic horizontal fruit-fly trap was not effective when similarly baited with ammonium cabonate. When used as attractants in the standard sticky trap, the following materials, in decreasing order of effectiveness with respect to total catch, attracted predominantly male walnut husk flies: oil of angelica seed, 97% males; sec-butyl 6-methyl 3- cydohexene-1-carboxylate, 80%; anisyl acetone, 74%; and methyl eugenol, 90%. The last two compounds were but weakly attractive.