Map the Spider

Help make a map for the Philadelphia purse-web spider

≈ 260 Entries

Last on:
30 May 2024

The project app is no longer accepting public sightings of purse-webs in the Philly area. Please see the website MAPTHESPIDER.COM for current information about the project.

Use BUGGUIDE.NET or INATURALIST.ORG to report webs and spiders.

Thank you! to the following volunteers who submitted data using this app: Heather S, John WG, Tom B, Bernard B, LJB, and Lauren H.

Steve T

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The Philadelphia area has a unique spider! (see

In the U.S. there are two known genera of purse-web spiders (Atypidae). The strictly North American genus Sphodros has 7 species found east of the continental divide, but we also have one enigmatic species in the genus Atypus normally associated with Europe and Asia. This spider was described in 1973 as Atypus snetsingeri and known - at that time - only from one site in eastern Delaware County, PA, near Philadelphia. A recent DNA analysis (published in 2022) has shown that our unique Atypus species is actually an introduced population of the east Asian species Atypus karschi Dönitz, 1887.

No one knows how long Atypus karschi has been here, but theoretically it could have hitched a ride as far back as 1784, hidden among potted plants, when direct shipping began from China to the port of Philadelphia in the newly-independent United States of America. Searches for webs in the region have shown that the spider is not uncommon, and can be found in habitats ranging from forest and woodlands to neighborhood hedges and gardens.

This project asks people to look for and report sightings of purse-webs in the Philadelphia region to help develop an accurate estimate of the introduced spider's current range and distribution.