Photos Of Female Ozyptila praticola With Egg Sac

Female Ozyptila praticola in repose,
with egg sac.

I've finally seen an Ozyptila praticola female with her egg sac! I've been so focused on determining the local range of this introduced European species in Washington state (USA), that I haven't spent much time delving into its life history. So for me, this was a first.

I found her in a cardboard live trap that I had placed in Kirkland, Washington back on 29 March 2018. The trap was a roll of 12" by 3" single-face flute-A corrugated cardboard placed under a layer of pine needles in a dry, shrubby area at Jasper's Dog Park. I returned this week to check the trap and found it inhabited only by the O. praticola, her egg sac, and a few earwigs.

Female Ozyptila praticola protecting
her egg sac

The egg sac was lenticular in shape and apparently "tacked" to the cardboard substrate at intervals with silk. The female was in repose on one side of the egg sac when I opened the trap. However, after I began to move the trap this way and that to get enough light for photos, she became active enough to take a more protective position over the egg sac.

If you're interested in this species, you should also check out Tone Killick's excellent photos of a female O. praticola and her egg sac, taken near Gloucester, England.

Ozyptila praticola In Tree Trunk Moss On The Cedar River

Site location map. Pins and circles indicate moss and cardboard
trap samples, respectively. Blue, yellow and red markers
indicate adult O. praticola, juvenile O. ?praticola, and no
O. praticola found, respectively.

My ongoing search for the outer edges of the local range of the introduced European spider Ozyptila praticola (Thomisidae) brought me recently to the Cedar River. This spring, I set out cardboard live traps at five locations along the Cedar River between 154th Place SE in Renton and Landsburg Road in Ravensdale, and later collected juvenile Ozyptila probably-praticola from traps at two of them. To confirm which species of Ozyptila was present, I re-set traps or sifted tree trunk moss at thirteen river valley sites between the Interstate 405 overpass in Renton and Landsburg Road in Ravensdale. Logistical constraints dictated which collection method I used.

Female Ozyptila praticola sifted from
tree trunk moss at Habenicht Park

To date, I have found mature O. praticola from the I-405 overpass to as far upstream as Fred V. Habenicht Rotary Park in Maple Valley (blue icons on map, above). Upstream of Habenicht Park, the only mature Ozyptila I've collected were the native O. pacifica. Notably, I didn't find O. pacifica at Habenicht Park or any site downstream from there. As I've mentioned before, I've never found the native O. pacifica and the introduced O. praticola present at the same location.