Grass Spider, Funnel Weaver, House Spider
Agelenopsis pennsylvanica (or related Agelenopsis / Eratigena species)
Agelenidae (Funnel-Weavers), Order Araneae. Key family characteristics include prominent spinnerets at the rear of the abdomen, specialized sheet-like webs ending in a funnel retreat, and a generally robust build adapted for running fast on low vegetation and ground surfaces.
Physical Description
The spider features a robust, elongated body with a distinct, oval-shaped abdomen and a somewhat flattened cephalothorax marked by characteristic dark longitudinal stripes. It has a velvety texture due to a fine covering of hairs. Highly visible, elongated spinnerets project from the rear tip of the abdomen, which are a hallmark of the family.
Size Estimate
Body length is approximately 10 to 18 millimeters (excluding legs), with a leg span reaching up to 40 to 50 millimeters. This specimen appears to be a sub-adult or adult medium-sized funnel weaver.
Coloration & Markings
Predominantly brown and grayish tones with distinctive longitudinal dark brown or black stripes running along the sides of the cephalothorax. The abdomen features a mottled pattern with a lighter, sometimes yellowish or grayish median band flanked by darker borders.
Web Type
Builds a horizontal sheet web consisting of non-sticky, densely woven silk that spans low vegetation, grass, or structural corners, leading back into a tubular retreat or funnel where the spider waits in ambush.
Eye Arrangement
Eight eyes arranged in two distinct, slightly curved rows of four. The eye arrangement is compact, typical of funnel weavers, allowing a wide field of vision to detect incoming prey or threats near their sheet web.
Leg Characteristics
Long, slender legs equipped with numerous visible spines used for traction and defense. The legs are generally brown with faint darker banding and are held in a wide, sprawling posture typical of ground-active hunting and web-dwelling spiders.
Venom & Safety Information
Venom Information
Neurotoxic/cytotoxic venom designed primarily to immobilize small insect prey quickly. It has very low potency relative to humans and is generally considered non-hazardous.
Medical Significance
Harmless to humans. Bites are rare, usually occurring only when accidentally compressed. Symptoms are typically minor, restricted to localized temporary pain, mild redness, or swelling comparable to a mosquito bite.
Safety Recommendations
To avoid encounters, seal cracks around doors and windows. If found trapped in a slick surface like a bathtub, safely relocate the spider outdoors using a glass and a piece of paper. No special pest control measures are required.
Habitat & Behavior
Habitat & Range
Found throughout North America and parts of Europe and Asia, inhabiting grassy fields, gardens, lawns, and frequently wandering into human dwellings, particularly basements, sinks, and bathtubs where they seek moisture.
Behavior & Temperament
Fast and agile runners. They are notoriously skittish and prefer to flee rapidly into their funnel retreats rather than confront threats. They are non-aggressive toward humans and will only bite if firmly trapped against the skin.
Diet & Prey
Carnivorous generalist predator. Feeds on ground-dwelling or low-flying insects such as crickets, flies, beetles, moths, and other small arthropods that blunder onto their sheet webs.
Seasonal Activity
Most active during late summer and autumn when adult males actively wander in search of females. They overwinter primarily as eggs within protected sacs.
Description
The grass spider or funnel weaver is a familiar sight in gardens and homes alike. Recognized by its prominent spinnerets and rapid running speed, it constructs intricate sheet webs that funnel into a cozy retreat. While their sudden movements can startle homeowners when found in sinks or bathtubs, these spiders are completely harmless and act as excellent natural pest controllers.
Key Features
Prominent, elongated spinnerets at the rear of the abdomen, dark longitudinal stripes on the cephalothorax, and construction of a sheet web ending in a funnel retreat.
Similar Species
Hobo spiders (Tegenaria agrestis) and Giant House Spiders (Eratigena atrica) share a similar appearance and family, but differ in geographic distribution, exact stripe clarity, and habitat preferences.
Life Cycle
Females construct tough, disc-like silk egg sacs in sheltered spots during autumn, depositing dozens to hundreds of eggs. Spiderlings hatch the following spring, undergo multiple molts, and reach maturity by late summer or autumn.
Ecological Importance
They play an important regulatory role in managing insect populations in gardens, lawns, and around human structures, serving as a vital link in the local food web.
Conservation Status
Not evaluated by the IUCN, but populations are exceptionally stable, widespread, and common across their native ranges.
Interesting Facts
Grass spiders do not use sticky silk to trap prey; instead, their sheet webs rely on dense interlaced threads that tangle the insect's legs, allowing the spider to rush out at incredible speeds.
Photography Tips
Photograph from a slightly elevated side angle to clearly capture the diagnostic longitudinal stripes on the cephalothorax and the elongated spinnerets at the rear of the abdomen. Use natural or diffused lighting to minimize harsh reflections from smooth surfaces.
Identified: 2026-09-09T13:49:44.918074