Joro Spider, Joro-gumo
Trichonephila clavata
Araneidae (Orb-Weavers), Order Araneae. Characterized by building vertical orb-shaped webs and having eight similar-sized eyes.
Physical Description
Elongated cylindrical abdomen with distinct patterns, a silver-grey or whitish carapace, and long legs featuring prominent tufts of setae. Marked sexual dimorphism is present, with females being significantly larger and more brightly colored than males.
Size Estimate
Females have a body length of 20 to 30 mm and a leg span up to 70 to 100 mm. This specimen appears to be an adult female.
Coloration & Markings
Bright yellow and dark blue/black transverse bands and patches along the elongated abdomen, contrasting with a pale silver-white cephalothorax and black-and-yellow banded legs.
Web Type
Large, permanent, three-dimensional vertical orb web constructed with characteristically golden-hued silk, often built between trees or structures.
Eye Arrangement
Eight small eyes arranged in two rows on a slightly raised tubercle on the clypeus, typical of the orb-weaver family.
Leg Characteristics
Long, slender legs featuring distinct black and yellow banding with dense brushes of dark hair (setae) on the tibia segments.
Venom & Safety Information
Venom Information
Contains low-potency neurotoxin used to immobilize small insect prey. Harmless to humans and larger pets.
Medical Significance
Not medically significant. A bite may cause minor, localized pain or redness similar to a mosquito bite, fading quickly without professional medical treatment.
Safety Recommendations
Leave undisturbed in its web. If relocation is necessary, gently guide the spider into a container using a stick. No pest control measures are necessary as they are harmless and beneficial.
Habitat & Behavior
Habitat & Range
Native to East Asia (Japan, Korea, China, Taiwan), recently established in the southeastern United States. Prefers forested areas, woodland edges, gardens, and urban spaces where it anchors large webs.
Behavior & Temperament
Docile and non-aggressive. It hangs head-down in the center of its large orb web waiting for prey, retreating when disturbed rather than biting.
Diet & Prey
Generalist insectivore feeding on flying insects such as mosquitoes, flies, beetles, stink bugs, and butterflies caught in its strong golden web.
Seasonal Activity
Peak activity occurs in late summer and autumn when females reach maximum size, spin large webs, and lay eggs before dying off with the first hard frosts.
Description
The Joro Spider is a striking orb-weaver known for its vibrant yellow and blue-black coloration and impressive golden webs. Recently introduced to North America, it has become a fascinating subject for homeowners and researchers alike due to its striking appearance and role as a beneficial predator of garden pests.
Key Features
Elongated yellow-and-black patterned abdomen, silvery carapace, distinctly banded black-and-yellow legs with brush-like setae, and large golden silk orb web.
Similar Species
Trichonephila clavipes (Golden Silk Orb-Weaver), which features a differently shaped abdomen and lacks the distinctive blue-black and yellow block patterns of the Joro spider.
Life Cycle
Females produce a brownish, papery egg sac containing hundreds of eggs in autumn. Spiderlings emerge in spring, disperse via ballooning, and mature by late summer.
Ecological Importance
Acts as an effective natural pest control agent by consuming large numbers of nuisance insects, including invasive species like the brown marmorated stink bug.
Conservation Status
Not evaluated by the IUCN; highly abundant in its native range and rapidly expanding and thriving in its introduced North American range.
Interesting Facts
Joro spiders are capable of 'ballooning,' using silk threads to catch the wind and travel long distances. Their silk shines with a distinct golden sheen in sunlight due to pigments that may provide UV protection and camouflage.
Photography Tips
Photograph from the side or slightly above to capture the full dorsal pattern and leg banding. Use a macro lens and indirect natural lighting to highlight the golden sheen of the web.
Identified: 2026-08-23T14:16:55.668564