Joro Spider, Joro-gumo
Trichonephila clavata
Araneidae (Orb-Weavers), Order Araneae. Key family characteristics include building vertical, wheel-like orb webs and having eight similar-sized eyes arranged in two rows.
Physical Description
Elongated, cylindrical abdomen with a distinct cephalothorax. Marked sexual dimorphism is present; females are significantly larger with bright contrasting colors, while males are much smaller and duller in appearance.
Size Estimate
Adult females have a body length of approximately 17 to 25 mm with a leg span reaching up to 70 to 100 mm. Males are much smaller, around 7 to 10 mm in body length.
Coloration & Markings
Features striking yellow and blue-cyan horizontal stripes across the dorsal side of the abdomen, interspersed with patches of red, particularly near the rear. Legs are banded in distinct black and yellow patterns.
Web Type
Large, three-dimensional orb webs featuring characteristic golden-hued silk. The web often spans across dense vegetation, trees, or structural corners outdoors.
Eye Arrangement
Eight small eyes arranged in two rows on a relatively compact cephalothorax, typical of orb-weaving spiders.
Leg Characteristics
Long, slender legs featuring noticeable dark and bright yellow or orange banding, often heavily spined to assist in prey capture.
Venom & Safety Information
Venom Information
Contains neurotoxic venom typical of orb-weavers, which is used to immobilize insect prey. It is low in potency relative to humans and is generally considered harmless.
Medical Significance
Not medically significant. A bite may cause localized pain, redness, or mild swelling similar to a mosquito bite, but they rarely bite humans.
Safety Recommendations
No special precautions needed beyond normal caution. If found near human activity, they can be gently relocated using a stick or container, though leaving them alone is entirely safe.
Habitat & Behavior
Habitat & Range
Native to East Asia (Japan, Korea, China, Taiwan) and recently introduced to the southeastern United States. Prefers forested areas, woodland edges, gardens, and around human structures where large flying insects are abundant.
Behavior & Temperament
Docile and non-aggressive. They spend most of their time stationary at the center of their large webs, retreating only when heavily disturbed.
Diet & Prey
Generalist predators feeding primarily on flying insects such as mosquitoes, flies, beetles, stink bugs, and wasps caught in their robust golden webs.
Seasonal Activity
Most active during the summer and early autumn months. Females lay eggs in late autumn and typically perish with the first hard frosts.
Description
The Joro Spider is a striking orb-weaver known for its brilliant yellow and blue-cyan banded body and massive golden webs. Native to Asia, it has successfully established populations in parts of North America, where it serves as a fascinating and harmless garden resident.
Key Features
Bright yellow and cyan abdominal stripes, distinctive red markings near the posterior, banded black and yellow legs, and large golden silk orb webs.
Similar Species
Argiope aurantia (Yellow Garden Spider) and Trichonephila edulis, distinguished by different ventral markings, abdominal shapes, and geographic distributions.
Life Cycle
Females produce an egg sac containing hundreds of eggs in the autumn. Spiderlings overwinter inside the sac and emerge in spring, ballooning to new locations to mature over the summer.
Ecological Importance
Acts as an effective natural pest controller by consuming large quantities of mosquitoes, stink bugs, and other nuisance insects, integrating well into local food webs.
Conservation Status
Not evaluated by the IUCN, but populations are robust and expanding rapidly in introduced ranges due to high adaptability.
Interesting Facts
Joro spiders are capable of 'ballooning,' using silken threads to catch the wind and travel long distances. Their silk has a distinct golden sheen that glitters in sunlight.
Photography Tips
Best photographed in natural daylight using a macro lens from a short, safe distance. Backlighting helps highlight the unique golden sheen of their webs.
Identified: 2026-10-03T18:30:34.228192