American Grass Spider / Funnel Weaver
Agelenopsis pennsylvanica
Agelenidae (Funnel-Weavers), Order Araneae
Physical Description
Robust body with a distinctly marked carapace featuring two dark longitudinal bands, and an elongated oval abdomen that tapers toward the rear. Prominent, elongated spinnerets are visible extending from the posterior end of the abdomen.
Size Estimate
Body length typically ranges from 10 to 18 mm for females, with a leg span reaching up to 40 to 50 mm.
Coloration & Markings
Carapace is yellowish-brown to gray with two dark brown or black lateral stripes running lengthwise. The abdomen features a broad, pale central band bordered by darker, mottled brown and gray areas.
Web Type
A characteristic horizontal sheet web with a tubular retreat or funnel at one edge where the spider lies in wait.
Eye Arrangement
Eight eyes arranged in two slightly curved horizontal rows, set closely together on the anterior portion of the carapace, typical of funnel-weavers.
Leg Characteristics
Long, tapered legs covered in prominent spines and hairs, often showing faint dark banding. The legs are held flat and spread wide to rapidly detect vibrations across the web.
Venom & Safety Information
Venom Information
Neurotoxic venom specialized for subduing invertebrate prey quickly. It has very low potency regarding humans.
Medical Significance
Not medically significant. A bite may cause minor, localized pain or redness similar to a mosquito bite, fading quickly without professional medical treatment.
Safety Recommendations
No special precautions needed. Simply avoid direct handling if you wish to prevent accidental defensive bites, and gently relocate them using a cup if found indoors.
Habitat & Behavior
Habitat & Range
Found throughout North America in grassy fields, gardens, woodpiles, compost bins, and low vegetation where structural retreats can be established.
Behavior & Temperament
Extremely fast and skittish; retreats rapidly into its funnel when disturbed. They are non-aggressive toward humans and will only bite if tightly cornered or trapped against skin.
Diet & Prey
Generalist predators feeding primarily on ground-dwelling and flying insects such as flies, beetles, grasshoppers, and moths captured on the sheet web.
Seasonal Activity
Most active during the late summer and autumn months when adults reach maximum size and males actively wander in search of mates.
Description
This image showcases the classic architectural masterpiece of a funnel-weaver spider: a tightly spun horizontal sheet web anchored to a wooden structure, leading directly into a dark silk retreat tube. While the resident spider is hidden deep inside its funnel waiting for unsuspecting prey, the web itself acts as an effective seismic trap. These spiders are beneficial garden residents that help control insect populations in damp, organic-rich environments.
Key Features
Elongated posterior spinnerets, a horizontal sheet web ending in a funnel retreat, and two dark longitudinal stripes running down the carapace.
Similar Species
Tegenaria domestica (Barn Funnel Weaver) and Holena nemorensis, distinguished primarily by more subtle abdominal markings and specific habitat preferences.
Life Cycle
Females construct tough, disc-shaped silk egg sacs in protected crevices during autumn, where eggs overwinter until spiderlings hatch in spring to begin rapid growth.
Ecological Importance
Serves as an effective natural pest control agent by consuming large numbers of insects in gardens, compost areas, and agricultural fields.
Conservation Status
Common and widespread with stable populations; not evaluated by the IUCN as they face no significant conservation threats.
Interesting Facts
Grass spiders possess some of the fastest acceleration rates among arthropods when rushing out of their funnels to capture prey.
Photography Tips
Focus sharply on the opening of the funnel retreat using macro settings, and wait patiently with a stationary camera for the spider to peer out.
User Notes
Found in compost bin
Identified: 2026-09-12T21:49:33.571320