American Grass Spider, Grass Spider, Funnel-Weaver
Agelenopsis pennsylvanica
Agelenidae (Funnel-Weavers), Order Araneae. Key family characteristics include long spinnerets extending past the posterior end of the abdomen and a characteristic funnel-shaped web.
Physical Description
Elongated body shape with a distinct cephalothorax marked by two dark lateral stripes and a tapered abdomen. The body texture is covered in fine setae (hairs), giving it a slightly velvety or bristly appearance. It has visible, prominent spinnerets at the rear.
Size Estimate
Body length ranges from 10 to 18 millimeters for females, slightly smaller for males, with a total leg span reaching up to 40 to 50 millimeters.
Coloration & Markings
Predominantly brown and tan coloration. The cephalothorax features dark brown lateral bands running lengthwise. The abdomen typically has a central lighter band bordered by darker mottled patches, providing effective camouflage in vegetation.
Web Type
Builds a horizontal, sheet-like web that does not stick, leading into a tubular retreat or funnel where the spider waits. Often found in grass, low shrubs, or corners of human structures.
Eye Arrangement
Eight eyes arranged in two slightly curved rows of four. The anterior row is more or less straight, while the posterior row is procurved. All eyes are dark and similar in size, typical of wandering or web-dwelling hunters of this family.
Leg Characteristics
Long, slender legs covered in numerous prominent spines and bristles, adapted for rapid running across vegetation and the non-sticky sheet web. Legs often show faint dark banding.
Venom & Safety Information
Venom Information
Contains neurotoxic venom tailored for subduing small insect prey. It is not potent or dangerous to humans.
Medical Significance
Harmless to humans. While they are physically capable of biting if pressed directly against the skin, the bite is generally no more painful than a mild bee sting and carries no medically significant systemic risks.
Safety Recommendations
No special precautions needed. If found inside, simply use a cup and a piece of cardstock to gently relocate the spider outdoors to the lawn or garden.
Habitat & Behavior
Habitat & Range
Found widely across North America, inhabiting open grassy fields, lawns, meadows, gardens, and occasionally straying into the corners of basements or outbuildings.
Behavior & Temperament
Extremely fast runners. They are timid and prefer to retreat rapidly into their funnel webs when disturbed rather than bite. Active hunters on their sheets, they rush out to capture prey that lands on the web.
Diet & Prey
Generalist insectivore feeding on grasshoppers, flies, beetles, moths, and other small arthropods that venture onto the horizontal web sheet.
Seasonal Activity
Most active during the late spring, summer, and early autumn. Mature adults are most commonly encountered in late summer and fall during their mating season.
Description
The American Grass Spider is a familiar and beneficial resident of lawns and gardens. Known for constructing intricate sheet webs that end in a dark funnel retreat, this spider spends much of its time waiting near the entrance for an unsuspecting insect to land. With its swift movements and distinctive striped cephalothorax, it is a fascinating predator that plays an important role in controlling garden insect populations.
Key Features
Prominent, elongated spinnerets at the rear of the abdomen, dark longitudinal stripes on the cephalothorax, and construction of a horizontal sheet web ending in a funnel retreat.
Similar Species
Wolf spiders (Lycosidae) and nursery web spiders (Pisauridae), but these do not build funnel-shaped sheet webs and lack the distinctly elongated spinnerets characteristic of grass spiders.
Life Cycle
Females construct silken egg sacs in sheltered spots under bark, rocks, or structures in the autumn. Spiderlings hatch in the spring, undergo multiple molts, and reach maturity by late summer.
Ecological Importance
Acts as an effective natural pest control agent in yards and agricultural settings by reducing populations of herbivorous insects.
Conservation Status
Not evaluated by the IUCN, but populations are secure, widespread, and abundant throughout their natural range.
Interesting Facts
Grass spiders are among the fastest terrestrial invertebrates relative to their size, capable of explosive acceleration when chasing prey across their sheet webs.
Photography Tips
Photograph from a top-down or slight side angle to capture the striped cephalothorax and the prominent spinnerets. Use natural, diffused lighting and a macro lens while keeping a respectful distance to avoid startling the spider into its funnel retreat.
Identified: 2026-08-12T01:17:44.104612