Joro spider, Joro-gumo
Trichonephila clavata
Araneidae (Orb-Weavers), Order Araneae. Key family characteristics include the construction of spiral orb webs, eight similar eyes, and robust bodies designed for holding prey in webs.
Physical Description
The spider has a distinctively elongate, cylindrical abdomen and a dark cephalothorax. Marked by prominent sexual dimorphism, females are significantly larger with bright coloration, while males are much smaller and duller in appearance.
Size Estimate
Female body length ranges from 17 to 25 mm with a leg span up to 70-80 mm. The specimen shown is likely a subadult or adult female.
Coloration & Markings
Features striking bright yellow and dark grey or black transverse bands across the dorsal abdomen, accompanied by reddish markings near the underside and dark legs with bright yellow or greenish-yellow banding.
Web Type
Builds large, three-dimensional orb webs characterized by a distinct golden-hued silk that shines brightly in direct sunlight. Placed between trees, shrubs, or along exterior structures of buildings.
Eye Arrangement
Consists of eight small eyes arranged in two rows on a compact eye tubercle, typical of orb-weaving spiders.
Leg Characteristics
Long and slender legs with prominent dark coloration interspersed with distinct yellow banding, often held in pairs when resting on the web.
Venom & Safety Information
Venom Information
Contains neurotoxic venom used primarily to subdue insect prey. The venom has very low potency regarding humans and is not medically significant.
Medical Significance
Harmless to humans and pets. A bite is extremely rare, comparable to a mild wasp sting in terms of localized pain and redness, and resolves quickly without professional medical treatment.
Safety Recommendations
No special safety measures are required as they are harmless. If found near doorways, they can be gently relocated using a stick or broom to a nearby bush or tree.
Habitat & Behavior
Habitat & Range
Native to East Asia (Japan, Korea, China, Taiwan) and recently established in the southeastern United States. Found in forests, woodlands, gardens, and around human habitations, spinning webs between vertical structures.
Behavior & Temperament
Docile and non-aggressive. They spend most of their time stationary at the center of their large orb webs, waiting for prey, and will retreat or drop from the web when severely disturbed.
Diet & Prey
Generalist predators feeding primarily on flying insects such as mosquitoes, flies, grasshoppers, and beetles caught in their strong orb webs.
Seasonal Activity
Most active and noticeable during the warm summer and autumn months, with females reaching maximum size and visibility by September and October before dying off after laying eggs.
Description
The Joro spider is a magnificent and visually striking orb-weaver native to Asia that has successfully expanded its range into parts of North America. Known for its brilliant yellow and black striped body and large golden webs, this arachnid is a fascinating addition to local ecosystems, helping naturally control pest insect populations.
Key Features
Brilliant yellow and black striped abdomen, dark legs with yellow banding, large golden-hued orb web, and distinctly elongate body shape.
Similar Species
Argiope aurantia (Black and Yellow Garden Spider), which features a more oval-shaped abdomen and distinct zigzag stabilimentum in the web compared to the cylindrical body and golden silk of the Joro spider.
Life Cycle
Females produce brownish egg sacs containing hundreds of eggs in protected crevices during autumn. Spiderlings hatch in spring, disperse via ballooning, and mature by late summer.
Ecological Importance
Acts as a beneficial generalist predator helping to control nuisance insect populations, including invasive species like the brown marmorated stink bug.
Conservation Status
Not evaluated by the IUCN, but highly abundant and expanding its introduced range rapidly in North America.
Interesting Facts
Joro spiders are exceptional aeronauts, using silk threads to catch the wind and 'balloon' hundreds of miles. In Japanese folklore, the 'Joro-gumo' is a mythical creature that can transform into a seductive woman.
Photography Tips
Photograph from the side or slightly above the web using natural backlighting to highlight the unique golden sheen of the silk and the vibrant yellow and black abdominal banding.
Identified: 2026-09-03T01:14:33.667417