Detecting / Delimiting T. oleracea Distribution in Washington State

As mentioned above, efforts to identify T. oleracea larvae were unsuccessful, which precluded the use of larval collection as a detection or delimiting technique in this project. The development of a dependable larval identification technique could facilitate future surveys, but more importantly, is a critical prerequisite to future work on the biology and impacts of T. oleracea in North America.

The first identified adult T. oleracea specimens found via this project were confirmed by Prof. George Byers, University of Kansas (Systematic Entomology Lab collaborating scientist), May 6, 1999, and consisted of 4 adults collected at two very interesting locations Two of the confirmed specimens, which were the first adult T. oleracea collected in 1999, actually came from Western Oregon, captured at the Salem area residence of Dr. Barry Bai, Entomologist with the Oregon Department of Agriculture. They were two male T. oleracea, captured by hand at the Bai residence by Todd Murray on April 1, 1999. The other two confirmed specimens were two adult female T. oleracea, collected July 20,1998 in light trap sampes at the authors residence near Tenino, in Thurston county, Washington State. Those adult female specimens, collected 1998, are currently the first recorded U.S. collections.

The simultaneous confirmation of T. oleracea collections from Thurston county, Washington, and the Salem area in Marion county, Oregon, rather abruptly established a (likely contiguous) distribution of T. oleracea that spans all of Western Washington (Figure 9). The distance from Salem, Oregon to Vancouver, Canada is approximately 375 miles. With the apparent early flight season establishment of contiguous distribution of T. oleracea across the Western Washington survey area, subsequent adult collections were continued with the objective of determining adult flight phenology. All together, 56 adult T. oleracea were collected in four Western Washington counties in this survey, including 3 in 1998 and 53 in1999, with the total number collected by county as follows: Whatcom - 32, King - 1, Pierce - 7, Thurston - 16.