Joro Spider, Jorogumo
Trichonephila clavata
Araneidae (Orb-Weavers), Order Araneae
Physical Description
The Joro spider exhibits extreme sexual dimorphism, with females being large, brightly colored, and possessing an elongated, cylindrical abdomen. The cephalothorax is dark with silvery hairs, and the legs are long and distinctly banded.
Size Estimate
Adult females have a body length of 17 to 25 mm and a leg span reaching up to 70 to 100 mm. Males are significantly smaller, typically around 6 to 10 mm in body length.
Coloration & Markings
Females feature striking yellow and blue-green transverse stripes across the dorsal side of the abdomen, with a vibrant red or orange patch typically located on the underside near the base. The long legs display prominent black and yellow or golden banding.
Web Type
Constructs large, highly visible vertical orb webs that can span several feet across, characterized by a distinct golden hue to the silk threads when catching sunlight.
Eye Arrangement
Eight small eyes arranged in two rows on a dark anterior tubercle, typical of orb-weavers, with lateral eyes grouped closely together.
Leg Characteristics
Legs are extremely long, slender, and heavily spined. They feature dark segments interspersed with bright yellow or yellowish-white banding and are often held in pairs.
Venom & Safety Information
Venom Information
Possesses mild neurotoxic venom used primarily to subdue insect prey. It is not considered medically significant to humans.
Medical Significance
Harmless to humans and pets. A bite may cause minor, localized pain, redness, or swelling similar to a mosquito bite, but they rarely bite unless firmly pressed against human skin.
Safety Recommendations
No special precautions needed beyond standard observation. If found near a doorway, they can be gently relocated using a stick or container to guide them to a nearby tree or bush.
Habitat & Behavior
Habitat & Range
Native to East Asia including Japan, Korea, Taiwan, and China. Recently established as an invasive species in the southeastern United States, preferring forests, gardens, and urban structures for web attachment.
Behavior & Temperament
Docile and non-aggressive toward humans. They remain stationary at the center of their large orb webs during the day, waiting for prey, and will retreat or drop from the web only when heavily disturbed.
Diet & Prey
Generalist predators feeding primarily on flying insects such as mosquitoes, flies, grasshoppers, and beetles caught in their sturdy orb webs.
Seasonal Activity
Most active and visible during the late summer and autumn months when females reach maturity and build their massive webs. Mating occurs in autumn before adults die off with the first hard frosts.
Description
The Joro spider is a magnificent and visually striking orb-weaver renowned for its brilliant yellow and blue-green coloration and large golden webs. Originating from Asia, it has successfully adapted to parts of North America, where its expanding populations fascinate nature enthusiasts and researchers alike. Despite its large and imposing size, it is a shy, beneficial predator that poses no threat to humans.
Key Features
Brilliant yellow and blue-green striped cylindrical abdomen, vibrant red underside markings, highly contrasting black and yellow banded legs, and large golden-hued orb webs.
Similar Species
Argiope aurantia (Yellow Garden Spider) and Trichonephila plumipes (Golden Silk Orb-Weaver). Joro spiders are distinguished by their specific blue-green and yellow stripe pattern and the distinct red patch on the ventral side of the abdomen.
Life Cycle
Females lay egg sacs containing hundreds of eggs in autumn, which overwinter and hatch in spring. Spiderlings disperse via ballooning in late spring, reaching adulthood by late summer.
Ecological Importance
Acts as an effective natural pest controller by consuming large quantities of nuisance and agricultural insect pests. They also serve as a food source for local birds and larger predators.
Conservation Status
Not evaluated by the IUCN, but highly abundant and expanding its invasive range rapidly in the southeastern United States without major population threats.
Interesting Facts
Joro spiders are famous for 'ballooning,' a dispersal method where juveniles use silk threads to catch the wind and fly long distances. Their silk has a brilliant golden sheen that exceptionally reflects sunlight.
Photography Tips
Best photographed in natural sunlight to capture the golden sheen of the web and the vibrant yellow and blue-green hues of the abdomen. Use a macro lens from a safe distance without disturbing the web.
Identified: 2026-10-11T01:53:33.309989