A Joro spider range map is a photograph of a moving thing. It changes every season, and it changes fastest in the states at the edge. Every range claim below therefore carries the date it was true, so this page ages honestly instead of quietly going stale.
Where They Are Now
University of Georgia Extension Circular 1273, in its most recent revision (as of June 16, 2026), divides the United States range into two categories.
Established populations
- Georgia
- North Carolina
- South Carolina
- Tennessee
- Alabama
The same source adds that the species is spreading to adjacent regions from this core, which is a moving boundary rather than a line.
Isolated populations
- Maryland
- Virginia
- Pennsylvania
These are pockets well outside the contiguous range. They are not the same claim as “the Joro spider now lives across the mid-Atlantic.”
You will see larger state counts in circulation, some of them well into double figures. We are not repeating those here, because we could not trace them to a university extension service, a state or federal agency, or a named scientist. When they can be traced, this page will be updated and the date above will change with it.
The live map is the authority, not any prose list. EDDMapS publishes the current distribution for this species and is updated as new reports are reviewed and accepted.
Reading a Range Map
Two habits make range maps much less misleading.
- A dot is a report, not a population. One confirmed spider in a parking lot 400 miles from the nearest breeding population is a real record and tells you almost nothing about whether the species lives there.
- Reporting effort is not evenly spread. Joro Watch runs an annual contest precisely to concentrate reporting, which means a county can appear to gain spiders when what it actually gained was people looking. Density on a citizen-science map is partly a map of attention.
How the Range Moves
Two mechanisms, and they produce different shapes on a map.
Ballooning moves the edge outward. Spiderlings climb to a high point, release strands of silk, and let wind currents carry them. Penn State Extension reports that ballooning spiders can travel tens to hundreds of miles. University of Georgia Extension notes the silk strands catch wind currents that can carry them many miles, even between islands. Because this happens to enormous numbers of spiderlings at once each spring, it expands the range as a front.
Accidental human transport produces the outliers. The species reached North America in the first place as a hitchhiker in freight, and the same routes keep operating. This is the likelier explanation for a population appearing several states beyond the front than for a spiderling having flown there. It is also why the earliest Georgia records clustered near warehouse and distribution facilities on the Interstate 85 corridor.
How Far It Could Go
Andy Davis and Benjamin Frick at the University of Georgia compared Joro physiology against the related golden silk spider, which is confined to the Southeast by cold. Their 2022 paper in Physiological Entomology found the Joro spider has roughly double the metabolism, a heart rate 77 percent higher, and the ability to survive brief freezes that kill the golden silk spider. They concluded that Joros could probably survive throughout most of the Eastern Seaboard.
Penn State Extension puts a number on the cold end: the species thrives in areas where the average January temperature is 25 to 32 degrees Fahrenheit.
Hold those two things apart. A physiological ceiling describes where the animal could live. The map above describes where it has actually been recorded. The gap between them is large, and it is the reason a headline about Joro spiders reaching a city is usually about a single report rather than an arrival.
Report a Sighting
Joro Watch is run by the University of Georgia Center for Invasive Species and Ecosystem Health, and it feeds reports into EDDMapS, the national Early Detection and Distribution Mapping System. Reporting is how the map above gets built.
- Where to report: the report form at jorowatch.org, or eddmaps.org, or the EDDMapS mobile app for iOS and Android. The app works without a signal and uploads later, which matters on a trail.
- Include photographs. Reports are reviewed before they are accepted, and a clear image is what makes that review possible. The underside of the abdomen, with its red markings, is the most useful angle.
- Report the misses too. Joro Watch asks people who went looking and found nothing to file a negative record. Absence data is how researchers tell a real range edge from a gap in coverage.
- Private land is handled. Joro Watch notes that a report marked private is shown publicly only to the county level.
Check what you saw against the lookalikes first. Golden silk orb-weavers and garden spiders get reported as Joros constantly.
The 2026 Spotting Contest
Joro Watch has announced its fifth annual Joro Spider Spotting Contest (as of August 21, 2026). It runs from Monday, October 12 at 12:00 a.m. through Sunday, October 18 at 11:59 p.m. Only reports entered into the database during that window count toward it.
There is no limit on the number of reports you can file, and each one can carry up to four images. Reports go in through the Joro Watch website, eddmaps.org, or the EDDMapS app, which needs an EDDMapS account.
The timing is not arbitrary: mid-October sits inside the September-to-October observation peak, when adult females are largest and their webs are most conspicuous.
Questions
What states are Joro spiders in?
As of the June 16, 2026 revision of University of Georgia Extension Circular 1273, the Joro spider is established in Georgia, North Carolina, South Carolina, Tennessee, and Alabama, and is spreading to adjacent regions. The same source reports isolated populations in Maryland, Virginia, and Pennsylvania. Range data changes every season, so check EDDMapS for the current map rather than relying on any list, including this one.
What is the difference between an established population and an isolated record?
An established population is one that is breeding and persisting across an area year after year. An isolated population is a pocket well outside the contiguous range, usually assumed to have arrived by accidental human transport rather than by natural spread. The two are not the same thing, and treating a single outlying record as proof that a state is now Joro country overstates what the data shows.
How far north will Joro spiders spread?
Further than they have so far, on the physiology. A 2022 University of Georgia study by Andy Davis and Benjamin Frick, published in Physiological Entomology, found the Joro spider has roughly double the metabolism of the related golden silk spider, a heart rate 77 percent higher, and can survive brief freezes that kill it. The authors concluded that Joros could probably survive throughout most of the Eastern Seaboard. Penn State Extension notes the species thrives in areas where the average January temperature is 25 to 32 degrees Fahrenheit. Surviving somewhere and having arrived there are different claims.
How do Joro spiders travel so far?
Spiderlings balloon. They release strands of silk that catch wind currents and carry them away from where they hatched. Penn State Extension reports that ballooning can move them tens to hundreds of miles, and University of Georgia Extension notes the silk can carry them many miles, even between islands. Adults do not balloon, but they and their egg sacs get moved accidentally in vehicles and freight, which is how the species reached North America in the first place.
How do I report a Joro spider sighting?
Through Joro Watch, run by the University of Georgia Center for Invasive Species and Ecosystem Health, which feeds sightings into the national EDDMapS database. You can submit through the report form at jorowatch.org, through eddmaps.org, or using the EDDMapS mobile app for iOS and Android. Photographs help the reviewers confirm what you saw. If you went looking and found nothing, report that too: Joro Watch marks it as a negative record, and negative data is useful to researchers.
When is the 2026 Joro Spider Spotting Contest?
The fifth annual contest, Joro Watch 2026, runs from Monday, October 12 at 12:00 a.m. through Sunday, October 18 at 11:59 p.m. Only reports entered into the database during that window count. There is no limit on the number of reports, and each report can carry up to four images.
Sources
- University of Georgia Cooperative Extension. Joro Spider: Trichonephila clavata (Circular 1273). Revised June 16, 2026. https://fieldreport.caes.uga.edu/publications/C1273/
- EDDMapS, Early Detection & Distribution Mapping System, University of Georgia Center for Invasive Species and Ecosystem Health. Joro spider (Trichonephila clavata) — State Distribution. Accessed August 21, 2026. https://www.eddmaps.org/distribution/viewmap.cfm?sub=87670
- Joro Watch, UGA Center for Invasive Species and Ecosystem Health. Joro Watch Season and 2026 Spotting Contest. Accessed August 21, 2026. https://jorowatch.org/season/
- Joro Watch, UGA Center for Invasive Species and Ecosystem Health. Report a sighting. Accessed August 21, 2026. https://jorowatch.org/report/
- University of Georgia (Davis and Frick, Physiological Entomology). Joro spiders likely to spread beyond Georgia. March 3, 2022. https://news.uga.edu/joro-spiders-likely-to-spread-beyond-georgia/
- Penn State Extension. Jorō Spiders. September 8, 2025. https://extension.psu.edu/joro-spiders