Pennsylvania Grass Spider, American Grass Spider, Funnel Weaver
Agelenopsis pennsylvanica
Agelenidae (Funnel-Weavers), Order Araneae. Key family characteristics include three pairs of spinnerets (with the posterior spinnerets notably elongated), a cribellum-absent or modified spinning apparatus, and a tendency to build dense sheet webs ending in a funnel-shaped retreat.
Physical Description
The spider has an elongated body with a tapering, cigar-shaped abdomen and a distinctively patterned cephalothorax. The texture is lightly hairy, typical of funnel weavers. Sexual dimorphism is present, with females generally being larger and broader-bodied than males, while males possess visibly enlarged pedipalps used for reproduction.
Size Estimate
Body length ranges from 10 to 18 millimeters (excluding legs), with a total leg span reaching roughly 35 to 50 millimeters. This specimen appears to be an adult or sub-adult.
Coloration & Markings
The base coloration is a mix of brown, tan, and grey. The carapace (cephalothorax) features two distinct dark longitudinal stripes running parallel from the eyes down the sides. The abdomen has a central lighter band bordered by darker mottled brown areas, creating a camouflage pattern well-suited for blending into vegetation and bark.
Web Type
Builds a sheet web that is flat or slightly concave, non-sticky, and constructed horizontally close to the ground or within structural crevices. The web extends into a tubular funnel retreat where the spider lies in wait.
Eye Arrangement
Eight eyes arranged in two strongly curved, nearly parallel rows of four. The eyes are relatively equal in size and positioned across the front of the carapace, giving the spider a wide field of view for detecting incoming prey.
Leg Characteristics
Legs are moderately long, tapering, and armed with numerous prominent spines used for gripping prey and traction on the web. They display faint dark banding and are typically held sPREAd flat against the surface in an alert posture.
Venom & Safety Information
Venom Information
Venom is neurotoxic to small invertebrate prey, enabling rapid immobilization. It has very low potency regarding humans.
Medical Significance
Harmless to humans. They are not aggressive and rarely bite unless tightly squeezed or trapped against the skin. A bite may cause minor, localized pinching or temporary redness, requiring no special medical treatment.
Safety Recommendations
No special safety measures are required. If one is found inside the home, it can be gently guided into a container using a piece of cardstock and relocated outdoors to the garden.
Habitat & Behavior
Habitat & Range
Found widely across North America, particularly in the eastern and central regions. Prefers grassy fields, lawns, low shrubs, and around human habitations such as stone walls, porch corners, and siding.
Behavior & Temperament
Extremely fast runners when outside the web, though they prefer to stay near the safety of their funnel retreat. They are shy, non-aggressive, and will quickly dart into hiding if disturbed. They are active hunters within the confines of their webs.
Diet & Prey
Feeds primarily on crawling and flying insects such as grasshoppers, crickets, flies, beetles, and moths that happen to land on the sheet web.
Seasonal Activity
Most active during late spring through autumn, with adult specimens becoming exceptionally visible in late summer and fall as they reach maturity and seek mates.
Description
The Pennsylvania Grass Spider is a quintessential backyard architect, crafting intricate sheet webs that span across low foliage and structural corners. With its distinctive racing stripes and lightning-fast speed, this funnel weaver is an expert at ambushing unsuspecting insects. Though their webs may occasionally accumulate dust around human structures, these spiders are completely harmless and act as diligent pest controllers.
Key Features
Elongated spinnerets visible at the rear of the abdomen, distinctive dark longitudinal stripes on the carapace, and the characteristic sheet web terminating in a funnel retreat.
Similar Species
Wolf spiders (Lycosidae) look superficially similar due to brown coloration and stripes, but wolf spiders do not build sheet webs and carry their egg sacs attached to their spinnerets. House spiders (Tegenaria/Eratigena) are also similar but typically build denser, messier cobwebs indoors.
Life Cycle
Mating occurs in late summer and autumn. Females construct tough, disc-like silk egg sacs in protected crevices or under bark, depositing dozens to hundreds of eggs. Spiderlings hatch the following spring after overwintering, undergoing multiple molts to reach maturity.
Ecological Importance
Serves as an important generalist predator in terrestrial ecosystems, helping to regulate populations of grasshoppers, beetles, and various garden insect pests.
Conservation Status
Not evaluated by the IUCN, but populations are widespread, secure, and highly resilient to common human habitat modifications.
Interesting Facts
Grass spiders are among the fastest terrestrial arthropods relative to their size, capable of executing sudden high-speed sprints to capture prey or escape predators.
Photography Tips
Photograph from above or a slight side angle to capture the carapace stripes and abdominal patterns. Use natural morning light and a fast shutter speed to freeze movement, maintaining a safe distance to avoid startling the spider back into its funnel.
Identified: 2026-09-02T01:49:17.749042