Barn Spider, Barn Orb-Weaver
Araneus cavaticus
Araneidae (Orb-Weavers), Order Araneae. Characterized by robust bodies, sticky spiral orb webs, and eight similar-sized eyes.
Physical Description
Robust body with a hairy, rounded to oval-shaped abdomen that tapers toward the rear. Prominent cephalothorax and noticeable sexual dimorphism with females being significantly larger and heavier than males.
Size Estimate
Body length ranges from 12 to 22 mm for females, with a leg span of up to 40 to 50 mm. This appears to be an adult specimen.
Coloration & Markings
Variable coloration ranging from beige, tan, yellowish-grey to dark brown. The abdomen features a distinct, ornate leaf-like or herringbone pattern bordered by dark scalloped margins, sometimes showing pale spots.
Web Type
Vertical orb web constructed with sticky spiral threads, typically spanning 1 to 2 feet in diameter. Placed near structures like barns, porches, or wooded edges.
Eye Arrangement
Eight eyes arranged in two rows of four, typical of the orb-weaver family, with lateral eyes often grouped in pairs.
Leg Characteristics
Long and robust legs with prominent dark banding and noticeable spination. Held radially when resting on the web.
Venom & Safety Information
Venom Information
Mild neurotoxic venom used primarily to immobilize insect prey. Not potent or harmful to humans.
Medical Significance
Harmless to humans. Bites are extremely rare and typically only occur if the spider is squeezed or trapped against the skin, resulting in minor localized pain similar to a mild bee sting.
Safety Recommendations
No special precautions needed beyond normal caution. If relocation is necessary, gently guide the spider into a container using a piece of cardstock and release it outdoors.
Habitat & Behavior
Habitat & Range
Found throughout North America, particularly in temperate regions. Prefers rural and suburban areas, specifically around wooden structures, barns, sheds, fences, and forested margins.
Behavior & Temperament
Docile and non-aggressive. Nocturnal hunter that typically hides in a retreat during the day and sits at the center of its web at night.
Diet & Prey
Feeds on flying insects such as moths, flies, beetles, and mosquitoes caught in its vertical orb web.
Seasonal Activity
Most active and noticeable in late summer and autumn when females reach full adult size and construct webs near lights or buildings.
Description
The Barn Spider is a magnificent and harmless nocturnal orb-weaver often found gracing wooden structures and porches. With its intricate patterning and impressive size, it serves as a master architect of the night, spinning large vertical webs to catch pest insects while remaining completely docile toward humans.
Key Features
Distinctive leaf-like or herringbone pattern on a bulbous abdomen, hairy legs with dark banding, and construction of large vertical orb webs near human structures.
Similar Species
Cross Orb-Weaver (Araneus diadematus), which features a prominent white cross marking on the abdomen rather than the ornate herringbone pattern of A. cavaticus.
Life Cycle
Females produce a silken egg sac in autumn containing hundreds of eggs, which overwinter before spiderlings hatch in spring. Undergoes multiple molts to reach maturity by late summer.
Ecological Importance
Acts as a natural pest control agent by consuming large quantities of flying insects, mosquitoes, and agricultural pests, contributing significantly to local ecosystem balance.
Conservation Status
Secure and widespread throughout its native range; not assessed by the IUCN as it faces no major threats.
Interesting Facts
Barn spiders are famous in popular culture as the species representing Charlotte in E.B. White's classic novel 'Charlotte's Web', though the fictional character is a composite of several orb-weaving traits.
Photography Tips
Best photographed at night when the spider is active in the center of its web. Use a macro lens with a ring flash or off-camera lighting to highlight the intricate abdominal patterns without disturbing the animal.
Identified: 2026-08-30T22:52:20.036488