American Grass Spider, Funnel-web Spider
Agelenopsis species
Agelenidae (Funnel-Web Weavers), Order Araneae
Physical Description
Elongated, somewhat flattened cephalothorax with two prominent dark longitudinal stripes. The abdomen is typically teardrop-shaped and hairy, featuring a pair of unusually long, visible spinnerets at the rear. They are built for speed with a sleek, aerodynamic profile.
Size Estimate
Body length typically ranges from 10mm to 20mm (0.4 to 0.8 inches) for females; males are slightly smaller but with a similar leg span of 25mm to 40mm.
Coloration & Markings
Predominantly brown and tan. The cephalothorax features two dark parallel lines running from the eyes to the start of the abdomen. The abdomen usually has a lighter central stripe bordered by darker, wavy, or chevron-like markings.
Web Type
A flat, non-sticky sheet web that leads to a funnel-shaped retreat in one corner. These are typically built on low vegetation, grass, or in corners of structures.
Eye Arrangement
Eight eyes arranged in two rows that appear highly curved (procurved). The two rows form a distinctive pattern where the top row looks like a deep 'U' shape.
Leg Characteristics
The legs are long, bristly, and covered in fine hairs (setae). They are often banded with alternating light and dark brown rings and end in three claws for navigating silk sheets.
Venom & Safety Information
Venom Information
The venom is a complex mixture containing agelenitoxins (neurotoxins), but it is optimized for paralyzing small insects rather than vertebrates.
Medical Significance
Not medically significant to humans. Bites are rare due to their timid nature. If bitten, symptoms are usually less severe than a bee sting (mild redness, itching, or local swelling).
Safety Recommendations
No special safety measures required. If found indoors, they can be easily moved outside using the 'cup and paper' method. They prefer the outdoors and rarely thrive inside homes due to lack of humidity.
Habitat & Behavior
Habitat & Range
Common throughout North America (USA and Canada). They are ubiquitous in gardens, tall grass, shrubs, and frequently found near building foundations or window wells.
Behavior & Temperament
They are exceptionally fast-moving, active hunters that wait in their funnel retreat for vibrations on the sheet web. They are shy and non-aggressive, usually bolting into their retreat at the slightest disturbance.
Diet & Prey
Generalist predators consuming a variety of insects such as ants, grasshoppers, moths, and flies that land on their web. They rely on speed rather than sticky silk to overtake prey.
Seasonal Activity
Maximum visibility occurs in late summer and early autumn when adults reach full size and webs are largest. Activity ceases in winter.
Description
The American Grass Spider is a common sight in late summer landscapes. These spiders are architectural masters of the lawn, crafting vast silken sheets that become visible when dew clings to them in the morning. While they appear large and move with startling speed, they are harmless neighbors that provide excellent pest control services for home gardens.
Key Features
Distinctive long-tapered spinnerets, two dark longitudinal stripes on the carapace, and the characteristic funnel-retreat web structure.
Similar Species
Often confused with Wolf Spiders (Lycosidae), which do not build webs and have different eye arrangements, or the venomous Brown Recluse (Loxosceles reclusa), which lacks the abdominal markings and long spinnerets.
Life Cycle
Females lay egg sacs in autumn, often attached to bark or siding, which overwinter. Spiderlings emerge in spring. Adults typically live just one season, dying after the first heavy frost.
Ecological Importance
Crucial for controlling populations of garden pests. They act as a significant food source for birds and larger predatory insects.
Conservation Status
Not evaluated by the IUCN, but populations are stable and abundant throughout their range with no known threats.
Interesting Facts
Despite having a non-sticky web, they are one of the fastest spiders on land. Their long spinnerets allow them to rapidly 'paint' silk over prey once they have pounced.
Photography Tips
Focus on the long spinnerets and the eye pattern. Early morning is the best time to capture the beauty of their webs when dew highlights the silken architecture.
Identified: 2026-07-06T19:19:53.047735