American Grass Spider
Agelenopsis pennsylvanica
Agelenidae (Funnel Weavers), Order Araneae
Physical Description
Elongated body with a distinct, brownish-grey cephalothorax featuring dark lateral stripes. The abdomen is brownish with a mottled pattern and long, prominent spinnerets extending from the rear.
Size Estimate
Body length ranges from 10 to 18 millimeters, with a total leg span reaching up to 30 to 40 millimeters.
Coloration & Markings
Predominantly brown and grey with two dark longitudinal stripes running along the carapace. The abdomen features a central lighter band bordered by darker mottled markings.
Web Type
Constructs a sheet-like web on grass or near ground structures that funnels into a tubular retreat where the spider waits for prey.
Eye Arrangement
Eight eyes arranged in two curved rows, typical of the Agelenidae family, providing a wide field of vision for detecting motion.
Leg Characteristics
Long, slender legs with distinct spination and subtle dark banding, held flat against the surface when resting.
Venom & Safety Information
Venom Information
Contains mild neurotoxic venom used primarily to subdue small insect prey. Not medically significant to humans.
Medical Significance
Harmless to humans. Bites are rare and typically only occur if the spider is trapped directly against the skin, resulting in minor localized irritation.
Safety Recommendations
No special safety measures needed. If found indoors, gently cup them under a glass and release them outside.
Habitat & Behavior
Habitat & Range
Widely distributed across North America, commonly found in lawns, meadows, fields, and around the foundations of homes.
Behavior & Temperament
Very fast and skittish. When disturbed, they typically retreat rapidly into their funnel web rather than acting aggressively.
Diet & Prey
Insecitvorous, feeding primarily on grasshoppers, crickets, flies, and beetles that land on their sheet web.
Seasonal Activity
Most active during late summer and autumn when adults reach full size and seek out mates.
Description
The American Grass Spider is a familiar sight in late summer gardens, recognized by the intricate sheet webs it spins low to the ground. Extremely fast and vigilant, these spiders spend most of their time near the entrance of their silken funnel retreat, waiting for an unsuspecting insect to trigger the web.
Key Features
Prominent long spinnerets at the rear of the abdomen, dark longitudinal stripes on the carapace, and a sheet web ending in a funnel retreat.
Similar Species
Wolf spiders (Lycosidae) and nursery web spiders (Pisauridae), neither of which build funnel-shaped sheet webs.
Life Cycle
Females construct silken egg sacs in sheltered spots during autumn. Spiderlings emerge in spring and mature by late summer.
Ecological Importance
Acts as an effective natural pest control agent by consuming large quantities of agricultural and garden insect pests.
Conservation Status
Not evaluated by the IUCN, but populations are abundant, widespread, and stable.
Interesting Facts
Grass spiders possess some of the fastest reaction times in the animal kingdom, capable of detecting and responding to vibrations on their web in milliseconds.
Photography Tips
Use a macro lens with a fast shutter speed to capture details, as these spiders move very quickly. Shoot from a low angle near the web.
Identified: 2026-09-16T21:24:39.392250