Cobweb Spider: Rhomphaea fictilium

Subject: Strange Spider?
Location: Upstate New York
July 11, 2017 9:14 pm
Dear Bugman,
My son and I located what we believe to be some sort of spider weaving a web under our porch light. We were quite curious as to what type of spider it might be. I am thinking some type of Orb Weaver? Any help would be greatly appreciated. So sorry for the quality of the photos, the bug was quite small. Thank you.
Signature: Heather

Cobweb Spider

Dear Heather,
We believe we have correctly identified your spider as a Cobweb Spider in the family Theridiidae, and it is a species without a common name,
Rhomphaea fictilium, thanks to this BugGuide image.  According to BugGuide, it is:  “widely scattered in the U.S., but reportedly rare; also throughout most of Canada.”  We located this interesting information on Spiderbytes:  “As well as having wonderfully strange morphology, Rhomphaea have rather unusual habits. Most spiders are generalist predators, and spiders in the family Theridiidae typically build tangle webs that they use to catch crawling insects and other arthropods, including other spiders. Rhomphaea, unlike most of their relatives, specialize on hunting other spiders. They do sometimes build their own rudimentary webs from just a few silk lines, but they also enter the webs of other spiders and use aggressive mimicry to hunt their owners. Rhomphaea will pluck the web and produce vibrations that lure the resident spider out to investigate what they perceive to be prey caught in the web. The web-building hunter then becomes the hunted, tricked into the approaching the dangerous intruder. Rhomphaea fictilium have been reported to prey on other theridiids, orb-weavers (araneids), sheet-weavers (linyphiids) and others.”

Cobweb Spider

Wonderful!  Thank you so very much for your help.  It was fascinating to read about this spider.
Thank you,

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