American Grass Spider, Grass Funnel-Weaver
Agelenopsis pennsylvanica (or related Agelenopsis species)
Agelenidae (Funnel-Web Weavers), Order Araneae. Key family characteristics include three pairs of spinnerets with the posterior pair notably elongated, and building distinctive sheet-like webs that terminate in a funnel-shaped retreat.
Physical Description
Elongated body with a distinct, oblong abdomen tapering slightly toward the rear. The cephalothorax is narrower than the abdomen and marked by distinct longitudinal dark stripes. The texture appears moderately hairy, typical of agile ground-dwelling and grass-dwelling hunters.
Size Estimate
Body length typically ranges from 10 to 18 millimeters, with a leg span reaching up to 40 to 50 millimeters. This specimen appears to be a sub-adult or adult of medium size.
Coloration & Markings
Muted earth tones consisting of greyish-brown to yellowish-tan. The carapace features two prominent, dark parallel longitudinal bands running down its length. The abdomen exhibits a mottled pattern with a lighter central band bordered by darker lateral markings.
Web Type
Builds a large, non-sticky horizontal sheet web made of dense silk threads, extending across grass or low vegetation, leading into a tubular retreat (the funnel) where the spider lies in wait.
Eye Arrangement
Eight eyes arranged in two curved rows of four. All eyes are roughly similar in size and dark in color, spread across the anterior portion of the cephalothorax.
Leg Characteristics
Long, slender legs equipped with prominent spines used for gripping prey and navigating the silk sheet. The legs display faint alternating dark and light banding and are held flat in a sprawling posture.
Venom & Safety Information
Venom Information
Contains neurotoxic venom tailored for immobilizing small arthropods. It has very low potency relative to humans and is generally ineffective against large mammals.
Medical Significance
Harmless to humans. Bites are extremely rare because grass spiders prefer to flee. If a defensive bite occurs, it typically results in mild, temporary local irritation or minor redness comparable to a mosquito bite.
Safety Recommendations
No special precautions needed as they pose no danger. If one enters a home, it can be safely guided into a cup using a piece of card and released outdoors.
Habitat & Behavior
Habitat & Range
Found throughout North America in open fields, meadows, lawns, and gardens, commonly inhabiting tall grass, low shrubs, and sometimes the exterior foundations of buildings.
Behavior & Temperament
Extremely fast and skittish. They are ambush hunters that remain inside their funnel retreats until vibrations on the sheet web signal prey, at which point they rush out with blinding speed. They are non-aggressive toward humans and will flee rather than bite.
Diet & Prey
Primarily feeds on ground-dwelling and flying insects such as grasshoppers, beetles, flies, and moths that happen to land or crawl onto the horizontal sheet web.
Seasonal Activity
Most active during the warm spring, summer, and early autumn months. Adults peak in late summer and autumn, after which individuals die off, leaving overwintering eggs.
Description
The American Grass Spider is a familiar and harmless resident of lawns and meadows across North America. Instantly recognizable by the intricate sheet webs they spin close to the ground, these speedy hunters play an essential role in keeping insect populations in check.
Key Features
Prominent longitudinal stripes on the carapace, elongated posterior spinnerets often visible at the rear of the abdomen, and association with a horizontal sheet web ending in a funnel retreat.
Similar Species
Wolf spiders (Lycosidae) look superficially similar due to coloration and hunting habits, but wolf spiders do not build webs and lack the elongated spinnerets. Hobo spiders (Eratigena agrestis) belong to the same family and look very similar, requiring microscopic examination for definitive separation.
Life Cycle
Mating occurs in late summer or autumn. Females construct tough, disc-shaped silk egg sacs attached to protected surfaces or under bark, where they overwinter. Spiderlings hatch in spring and undergo multiple molts to reach maturity by late summer.
Ecological Importance
Acts as an effective natural predator of garden and agricultural pests, serving as a crucial link in the local food web for birds, small mammals, and predatory reptiles.
Conservation Status
Not evaluated by the IUCN, but populations are widespread, stable, and highly adaptable to human-altered landscapes like manicured lawns.
Interesting Facts
Grass spiders possess some of the fastest reaction times in the animal kingdom, able to detect and strike at prey on their webs in fractions of a second. Despite living in grass, they cannot climb smooth vertical surfaces very well.
Photography Tips
Photograph from above to capture the carapace stripes and abdominal pattern, or from the side to reveal the spinnerets. Use a fast shutter speed or flash to freeze movement, as these spiders are exceptionally quick.
Identified: 2026-08-21T02:41:19.901063