Friday, March 25, 2016

7-Mar-2016 U-W Campus, Washington

Site location map. Click to enlarge.
The day was dry and sunny but only about 50 degrees Fahrenheit, perfect weather to find insects and spiders on the sun-warmed sides of brick buildings.  So I decided to spend an hour on the University of Washington campus in Seattle attempting to find more of the introduced European jumping spider Pseudeuophrys lanigera.  I'm not quite satisfied with having documented only two populations in the area.

Oecobius navus on building exterior
Sitticus pubescens on building exterior
Spiders weren't as numerous on the buildings as I'd hoped, but I did find what was probably an Oecobius navus (Oecobiidae), and one female jumping spider.

Sitticus pubescens epigynum
As it turned out, the jumping spider wasn't a P. lanigera, but a different introduced European species, Sitticus pubescens!  This is only the second record of S. pubescens in Washington state.  The other was a male that Rod Crawford found a few years ago in Everett.

Eastern white pine
My search of building exteriors led me to the Communications Building, which has a huge eastern white pine (Pinus strobus) growing near its entrance.  Beneath the tree were hundreds of fallen cones, apparently undisturbed by groundskeepers.  How could I resist?!

Fallen pine cones on a sumptuous bed
of needle litter
I tapped 50 fallen cones and collected 7 spiders and two identifiable species: Ozyptila praticola (Thomisidae) and Diplostyla concolor (Linyphiidae), both also introduced European species.  I also tapped 6 harvestmen and countless sow bugs, snails and insects from these cones.

Tiny snails tapped from cones
I'm quite amused by how the search for one introduced species keeps leading to the discovery of another and yet another.  Last fall, while tapping cones in Mukilteo, Washington to determine the local range of the introduced species Ozyptila praticola, I discovered the presence of a different introduced species, Pseudeuophrys lanigera.  Then this day, when in search of more P. lanigera, I confirmed the presence yet another introduced species, Sitticus pubescens.  If I search for more S. pubescens elsewhere in the city, I wonder which "new" introduced species I'll find next.

Putting flies into perspective.

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