Joro spider, yellow and black orb-weaver
Trichonephila clavata
Araneidae (Orb-Weavers), Order Araneae. Characterized by building vertical, wheel-like orb webs and typically having robust bodies with long, spiny legs.
Physical Description
Elongated body with a distinct cephalothorax and cylindrical to slightly oval abdomen. Females are large with pronounced sexual dimorphism, while males are much smaller and drab in coloration. The carapace features fine hairs and distinct patterning.
Size Estimate
Adult females have a body length of about 17 to 25 millimeters and a leg span reaching up to 70 to 100 millimeters. Males are significantly smaller, around 7 to 10 millimeters in body length.
Coloration & Markings
Striking vibrant yellow and dark grey or black transverse stripes along the dorsal abdomen, accented by distinctive red or orange markings near the underside base. Legs feature prominent dark banding interspersed with yellowish sections.
Web Type
Large, vertical orb web characterized by distinctive golden-hued silk that glints in the sunlight. The web often includes a dense, messy barrier web surrounding the central orb structure.
Eye Arrangement
Eight eyes arranged in two rows, typical of orb-weavers, with lateral eyes often paired and median eyes situated on a slight raised tubercle.
Leg Characteristics
Extremely long, slender legs with conspicuous black and yellow banding. The legs possess prominent bristles and spination, and the spider typically rests in the center of the web with legs paired in an X-shape.
Venom & Safety Information
Venom Information
Neurotoxic venom primarily targeted at immobilizing small insect prey. It is relatively weak and generally ineffective against large mammals and humans.
Medical Significance
Harmless to humans. A bite may cause minor, localized pain, redness, or swelling similar to a mosquito bite, but it carries no medical danger or systemic risk.
Safety Recommendations
No special precautions needed. Enjoy observing them from a distance. If one builds a web in an unwanted location around the home, it can be gently relocated using a broom or stick.
Habitat & Behavior
Habitat & Range
Native to East Asia including Japan, Korea, China, and Taiwan. Recently introduced and established in the southeastern United States, preferring forests, woodlands, gardens, and human-made structures where it strings webs between trees and buildings.
Behavior & Temperament
Docile and non-aggressive. They spend most of their time stationary in the center of their large webs waiting for prey. When disturbed, they typically retreat to the edge of the web or drop to the ground rather than bite.
Diet & Prey
Generalist predators feeding primarily on flying insects such as mosquitoes, flies, beetles, stink bugs, and butterflies caught in their sturdy orb webs.
Seasonal Activity
Most active and noticeable during late summer and autumn when females reach maximum adult size and construct prominent webs. They overwinter in the egg stage.
Description
The Joro spider is a magnificent and visually striking orb-weaver renowned for its brilliant yellow and black coloration and massive golden silk webs. As an invasive species in North America, it has captured public attention due to its size and hardiness, while playing a beneficial role in controlling local insect populations without posing a threat to humans.
Key Features
Brilliant yellow and black striped abdomen, golden-tinted silk web, exceptionally long banded legs, and a tendency to rest in the dead center of a large vertical orb.
Similar Species
Argiope aurantia (Black and Yellow Garden Spider), which features a more oval, distinctly patterned abdomen and zig-zag stabilimentum silk structures in the web, unlike the golden web and elongate body of the Joro spider.
Life Cycle
Females lay egg sacs containing hundreds of eggs wrapped in silk in the autumn. Spiderlings hatch in spring, disperse via ballooning on silk threads, and mature through successive molting stages by late summer.
Ecological Importance
Act as efficient natural pest controllers by consuming large quantities of nuisance and invasive flying insects, fitting smoothly into local forest and garden food webs.
Conservation Status
Not evaluated by the IUCN, as populations are abundant and rapidly expanding in their introduced and native ranges.
Interesting Facts
Joro spiders are capable of 'ballooning,' using silken threads to catch the wind and travel long distances as spiderlings. Their golden silk is exceptionally strong and has been studied for biomaterial applications.
Photography Tips
Capture from the side or slightly above to showcase the striking dorsal yellow and black patterns. Backlighting can highlight the unique golden sheen of the web silk. Maintain a steady hand with a macro lens for fine leg details.
Identified: 2026-08-23T17:13:01.518432