Grass Spider, American Funnel-Web Spider
Agelenopsis sp. (likely Agelenopsis pennsylvanica or Agelenopsis naevia)
Agelenidae (Funnel-Web Weavers), Order Araneae
Physical Description
Elongated, somewhat flattened body structure with prominent, long prominent two-segmented posterior spinnerets visible at the tip of the abdomen. The cephalothorax is teardrop-shaped, and the elongated oval abdomen tapers towards the rear.
Size Estimate
Body length approximately 10–18 mm for adult females, leg span reaching 25–40 mm. The silhouette shown suspended or resting in/near the funnel web suggests an adult or subadult specimen.
Coloration & Markings
Typically light brown to grayish-tan with two dark longitudinal stripes running down the cephalothorax and a central dark chevron or folium pattern bordered by lighter stripes along the abdomen.
Web Type
Dense, sheet-like horizontal web tapering into a tube-like funnel retreat at one corner or edge. Built outdoors on railings, shrubs, grass, or corners of buildings.
Eye Arrangement
Eight eyes arranged in two strongly procurved rows of four, forming a distinct pattern on the anterior part of the cephalothorax.
Leg Characteristics
Long, relatively slender legs equipped with noticeable spines and dark banding or striping, optimized for fast running across the non-sticky surface of their sheet web.
Venom & Safety Information
Venom Information
Contains neurotoxic components (agatoxins) effective against insects, but harmless to humans due to low toxicity and small venom volume.
Medical Significance
Not medically significant. Bites are extremely rare because the spider retreats when disturbed. If a bite occurs, it typically results only in minor localized redness or mild irritation.
Safety Recommendations
Harmless nature partners that provide natural pest management. If web placement on a porch or railing causes discomfort, gently clear the web with a broom or relocate the spider using a container.
Habitat & Behavior
Habitat & Range
Widespread across North America. Commonly found in low vegetation, grasslands, suburban gardens, porches, window sills, and external house structures.
Behavior & Temperament
Extremely fast runners that rely on speed rather than sticky silk to capture prey. Shy and non-aggressive towards humans, quickly retreating into their funnel shelter when vibrations alert them to danger.
Diet & Prey
Generalist predators consuming flying and crawling insects such as moths, flies, crickets, beetles, and ants that land on the horizontal sheet of the web.
Seasonal Activity
Peak activity occurs in late summer and early autumn when adult spiders reach full size, construct prominent webs, and search for mates.
Description
Grass spiders of the genus Agelenopsis are master builders of expansive horizontal sheet webs that feature a hollow retreat funnel at one edge. Frequently seen on lawns, garden beds, and home exteriors, these light-brown arachnids are renowned for their lightning speed, darting out from their shelter the moment an unsuspecting insect falls onto the sheet.
Key Features
Distinguished by unusually long, prominent posterior spinnerets protruding from the abdominal tip, two dark longitudinal thoracic stripes, and a dense horizontal sheet web leading into a funnel retreat.
Similar Species
Often confused with Wolf Spiders (Lycosidae), which lack long spinnerets and do not build funnel sheet webs, and Hobo Spiders (Eratigena agricola/agrestis) or Barn Funnel Weavers (Tegenaria domesticus), which have different eye patterns and body markings.
Life Cycle
Annual life cycle. Females lay disc-like, white-to-tan egg sacs suspended near or inside the retreat during late summer/autumn. Offspring hatch in spring, mature through summer, and adults die off after winter freezes.
Ecological Importance
Crucial pest control agents around homes and gardens, consuming vast quantities of flying pests, agricultural insect pests, and crawling bugs.
Conservation Status
Not evaluated by IUCN, but extremely abundant and stable across its native North American range.
Interesting Facts
Grass spider silk is non-sticky; instead, the spider relies purely on immense speed to rush out and tackle insects trapped by the web's intricate mesh layer.
Photography Tips
Capture the spider from a top-down angle to highlight the thoracic stripes and long spinnerets. Macro focus on the head region reveals the distinctive eye arrangement.
Identified: 2026-07-24T22:00:37.921702