American Grass Spider, Grass Spider, Funnel-Weaver
Agelenopsis pennsylvanica
Agelenidae (Funnel-Weavers), Order Araneae. Key family characteristics include long, prominent posterior spinnerets and the construction of sheet webs ending in a tubular retreat.
Physical Description
Elongated body shape with a distinct pattern on the cephalothorax. The abdomen is oval and tapering, featuring long, visible spinnerets protruding from the rear. The overall texture is velvety with fine setae.
Size Estimate
Body length typically ranges from 10 to 18 mm for females, with a leg span reaching up to 30 to 50 mm. The specimen appears to be an adult or sub-adult.
Coloration & Markings
Features a light brown to yellowish-gray base coloration with two prominent, dark longitudinal stripes running along the length of the cephalothorax. The abdomen often has a darker central band bordered by lighter mottled patterns.
Web Type
Builds a dense, non-sticky horizontal sheet web (funnel web) close to the ground in grass or low vegetation, terminating in a tubular retreat where the spider waits for prey.
Eye Arrangement
Eight eyes arranged in two distinct, slightly curved rows of four. The anterior row is more curved, and the eyes are generally equal in size, typical of wandering and funnel-weaving spiders.
Leg Characteristics
Long, robust legs featuring distinct dark banding or rings, covered in numerous prominent spines used for tactile sensing and subduing prey. Legs are typically splayed outward on the web surface.
Venom & Safety Information
Venom Information
Contains neurotoxic venom used primarily to quickly immobilize insect prey. The venom is relatively weak and has no significant medical impact on humans.
Medical Significance
Not medically significant. They rarely bite humans, and a bite typically produces only mild, localized pain, slight redness, or swelling comparable to a minor mosquito bite.
Safety Recommendations
No special safety measures are necessary as they are harmless. If found indoors, they can be gently relocated outside using a cup and a piece of card.
Habitat & Behavior
Habitat & Range
Found throughout North America, heavily concentrated in grassy fields, lawns, meadows, and low shrubs where ground-level vegetation supports their sheet webs.
Behavior & Temperament
Highly alert and exceptionally fast runners. They are timid and non-aggressive toward humans, typically fleeing into their funnel retreat when disturbed rather than biting.
Diet & Prey
Generalist predators feeding on various ground-dwelling insects including grasshoppers, beetles, flies, and ants, captured when they land on the non-sticky sheet web.
Seasonal Activity
Most active during late summer and autumn when adults reach full size and males actively wander in search of mates before dying off before winter.
Description
The American Grass Spider is a familiar garden resident, easily recognized by the sprawling sheet webs it weaves across lawns and low bushes. As a member of the funnel-weaver family, it spends most of its time hidden inside a silken tube, darting out with incredible speed to capture unsuspecting insects that stumble across its web.
Key Features
Two dark longitudinal stripes on the carapace, elongated posterior spinnerets, and the classic flat sheet web ending in a funnel-shaped retreat.
Similar Species
Wolf spiders (Lycosidae), which do not build webs and have a different eye arrangement, and hobo spiders (Tegenaria agrestis), which possess more uniform coloration without the distinct carapace stripes.
Life Cycle
Females construct silk egg sacs in sheltered spots under rocks, bark, or debris in the autumn. Overwintering occurs in the egg stage, with spiderlings hatching in spring and maturing by late summer.
Ecological Importance
Serves as an effective natural controller of insect populations in gardens and grasslands while acting as a vital food source for birds, amphibians, and larger predators.
Conservation Status
Not evaluated by the IUCN, but populations are widespread, stable, and highly abundant across their native range.
Interesting Facts
Grass spiders possess some of the fastest acceleration rates among terrestrial animals when launching out of their funnel retreats to capture prey.
Photography Tips
Photograph from a low angle parallel to the web or ground in natural daylight. Use a fast shutter speed to capture details if the spider is active, and maintain a calm approach to avoid startling them into their retreat.
Identified: 2026-09-02T00:37:28.171553