ADULT FLIGHT DYNAMICS OF WALNUT HUSK FLY (DIPTERA, TEPHRITIDAE) IN THE WILLAMETTE-VALLEY OF OREGON

Seasonal flight of the walnut husk fly (WHF), Rhagoletis completa Cres son, was investigated using Pherocon AM traps in unsprayed trees, and commercial walnut orchards for a 4-year period (1990-1993). The adult emergence of WHF varied from year to year. The first flies in untreate d trees were detected from July 1 through July 17; with an average of July 9. Seasonal peaks were observed between August 10 and September 4 , and the last flies were trapped on September 11 through October 9. I n commercial orchards, the first flies were trapped July 13 through Au gust 5, seasonal peaks occurred around August 31 through September 9, and the last flies were trapped between September 14 through 30. Adult emergence occurred approximately two weeks later in commercial orchar ds. Only one generation per year was recorded. Dissections of females indicated that under field conditions, WHF was capable of egg laying 7 days after emergence, and females with mature eggs were found through out the walnut growing season.