About 'Map the Spider'
Hi. I'm Steve Tessler, site owner extraordonaire and project leader. Please pardon the awkwardness of the website layout etc. I'm currently typing HTML by hand to update things and barely know what I'm doing! And it shows. Let me know if you can help!
A little history
I've been casually recording places where I've found the webs since the 1970s when I was a student of Dr. Bob Snetsinger (really!). Being "from" Upper Darby near the Lansdowne site where the spider was 'discovered', I noticed lots of webs in the Darby and Cobbs creek drainages, and I'd look for them when I visited after moving out of the area. I moved back to SE Pennsylvania in the late 1990's but didn't get more serious about making a real map until 2012 when I found the spiders at Tyler Arboretum, where I have been a volunteer. In 2013 I got a visit from Milan Řezáč from the Czech Republic - an expert on European Atypidae - and showed him around to several sites where the spider occurred and we discussed all that I knew at that time (we recently collaborated on paper about the spider).
I made an Epicollect app in 2016 for my personal use to track my searches, and updated it in 2019 to Epicollect5 and started sharing it so that others could help me. I also launched this website in September 2019. Since the pandemic started in 2020 I've had more time to spend on the project - scanning satellite and street views on Google Maps to look for new sites to visit that might have webs - and mostly ignored the website until winter of 2022. I'm now looking into moving the site to Wordpress or some other platform so I can stop typing everything!
The project asks for your help to find purse-webs near your home or places you visit. If you are not sure if something is a purse-web or not, you'll need to gently touch it. The purse-web silk will 'give' a little when you touch it, while non-web things like roots and dirt-covered termite tunnels are rigid.
Goal 1: Find out how common purse-web spiders are. Most people would never notice a purse-web unless they were shown what one looked like and then actually looked for them. Despite their camouflage, purse-webs can be found at any time of year and with a little practice are not hard to spot from a distance. Often many webs are found close together on a tree, a wall or in shrubbery. In the Philadelphia area once you start looking you notice them everywhere.
Goal 2: Determine the range of the PA-local spider Atypus snetsingeri*. The current effort suggests that it is limited to southeastern Pennsylvania, from the Chester Creek valley in Delaware County eastward through the Schyulkill and Wissahickon valleys to the Pennypack Creek in Philadelphia and Montgomery Counties. These web sightings will lead to collections of spiders for formal identification and species confirmation. We're asking people in PA, NJ, and DE to report web sightings to provide a range of locations we can visit to get confirmed species IDs.
Goal 3: Develop non-destructive methods to tell the species apart.. Wandering males mostly look different, but these spiders spend 99.99% of their time within their webs hidden from view. How can we tell who lives in a web without disturbing the spider? One way is to look at the shed skins, or "exuviae," that often get stuck at the top of the purse-web when discarded. The exuviae preserve hard parts that we hope to use to distinguish different species, without digging up or killing any spiders.
Report purse-web sightings
Please use the MapTheSpider app to report sightings of purse-webs. The app is simple to use, works offline (away from cell towers) and only asks for the minimum information necessary to validate your sightings. Each Observer can use the app to track their own sightings and the places they visited, and at the same time it organizes all of the reported data for the project.
We also monitor the sites Bugguide.net and iNaturalist.org for reports of Atypidae sightings in our area but won't use those for the map without independent onsite verification of purse-webs present. While those sites are great for posting your pictures, our project's app includes important questions that need to accompany a web sighting.
Can we see your spiders??
Many good locations to look for spiders are on private property or 'Posted lands' that prohibit public access. Large areas on the current map that were not searched were MOSTLY because the land is private and not accessible by the public. If you have access to those areas and are willing to let us visit to take photographs and measurements, please let us know. Or if you have access to one of the many private woodlands or fenced-in corporate properties and can get permission for us to make a search, let us know. Send an email to .
Not sure if the webbing you see is a purse-web?
Other kinds of webs are present in the same habitats, but unless the web is ONLY a tube of silk it is not a purse-web. Check the pictures on this site and online. Purse-webs look tubular and sock-like, and will 'give' a little when you touch them with a blade of grass, while non-web things like roots are rigid. 'Tube-like' webs attached to silken sheets or platforms or a 3D trap in space are NOT made by purse-web spiders. For example, funnel-web spiders are common in the same places you find Atypids and make a sheet web that leads to a funnel with a hole, but those are not purse-webs.
Questions about spiders or webs?
Map The Spider is specifically interested in current reports of purse-web sightings in the Philadelphia area for building a map and collecting shed skins. If you have questions about any other spiders and invertebrates you find, including artifacts like webs, check out Bugguide.net or iNaturalist.org. Post a photo and volunteers will help you identify what you found, or just browse the images to see what others are seeing.Contact us at
* Note: Recent DNA evidence indicates that Atypus snetsingeri is actually an introduced naturalized population of Atypus karschi from east Asia. The name 'snetsingeri' will still be used here until the official synonomy is declared in the World Spider Catalog.