Saturday, May 16, 2015

2-Jul-2010 Horse Lake Mountain, Washington

Site locations
With cone tapping being such a new spider sampling method, Washington remained largely unsampled in 2010.  This meant that virtually any fallen cones I found, no matter where, were in uncharted territory and worthy of tapping.  So while our destination for the day was a mountain west of Wenatchee, a restroom break along the way at Nason Creek Rest Stop on SR 2 seemed to me as good a time and place as any to collect a tapping sample.

Cones along back fence of Nason
Creek Rest Stop...
...and even more cones in lightly used
picnic area
Plenty of fallen ponderosa pine (Pinus ponderosa) cones were available in two of the lesser-used corners of the rest area.  Tapping 60 cones I collected 13 spiders and 5 species.  Among them were two specimens of Theridion rabuni (Theridiidae), a species that has, so far, been found in Washington only in tapped pine cones.

Hillside sampling site at
Horse Lake Mountain
Pines in meadow at
Horse Lake Mountain
I sampled two cone sources at Horse Lake Mountain, our day's destination: stands of ponderosa pine growing in a lush grassy meadow, and an open ponderosa pine forest growing on the surrounding hillsides.  I tapped 100 cones from each source, and collected a decidedly non-diverse sample.  The meadow cones produced 8 spiders, all of them Euryopis formosa (Theridiidae) except for one jumping spider.  The hillside cones produced 9 spiders, all E. formosa.

Female, male and juvenile E. formosa were all present in both of my Horse Lake Mountain samples.  After additional years of sampling I have observed that both sexes are usually present in cones between late June and mid-July, with juveniles being the only life stage reliably found in other months.  However, I have not sampled fallen cones in eastern Washington intensively enough in August and September be too certain about the timing of the end of E. formosa's adult seasonality in cones.

Be sure to read Rod's take on the day here!

An Acmon blue (Plebejus acmon) nectaring on yarrow (Achillea millefolium)

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