Grass Spider, American Grass Spider, Funnel-Weaver
Agelenopsis species (likely A. pennsylvanica or A. naevia)
Agelenidae (Funnel-Weavers), Order Araneae
Physical Description
Elongated, robust body with a distinct pear-shaped cephalothorax and an oval-to-tapered abdomen. It features prominent, long spinnerets visible at the rear of the abdomen, which are a diagnostic trait of the family. The body is covered in fine hairs.
Size Estimate
Body length typically 10-20mm (approx. 0.5 to 0.75 inches); total leg span can reach 2 inches. This appears to be an adult specimen.
Coloration & Markings
Background color is tan to light brown. The cephalothorax has two prominent dark longitudinal parallel stripes. The abdomen features a central brown band often outlined by lighter cream or gray markings in a chevron-like pattern.
Web Type
Funnel web. Large, flat, non-sticky horizontal sheets that taper into a silk tube or 'funnel' where the spider hides. Usually built in grass, low shrubs, or corners of structures.
Eye Arrangement
Eight eyes arranged in two rows that appear strongly procurved, forming a circular or U-shaped pattern when viewed from above.
Leg Characteristics
Long, agile legs designed for speed. They are light brown with darker banding or mottling and possess numerous small spines (setae). The legs lack the heavy padding (scopulae) found in hunting spiders like Wolf Spiders.
Venom & Safety Information
Venom Information
Contains agelenitoxins (acylpolyamine neurotoxins) used to paralyze insect prey. The venom is not considered medically significant to humans.
Medical Significance
Low. Bites are rare as the spider is timid. If a bite occurs, symptoms are usually less severe than a bee sting, involving minor swelling, redness, and localized itching.
Safety Recommendations
If found indoors, they can be easily relocated using a cup and a piece of paper. They pose no threat to pets or humans. Sealing cracks in foundations can reduce the number of spiders entering the home in autumn.
Habitat & Behavior
Habitat & Range
Found throughout North America. Preferred habitats include lawns, pastures, low bushes, and the foundations of buildings. They frequently enter homes during the late summer and fall.
Behavior & Temperament
Extremely fast runners. They are ambush hunters that sit at the mouth of their funnel and dash out to grab prey that vibrates the silk sheet. They are generally shy and non-aggressive toward humans, preferring to retreat into their funnel.
Diet & Prey
Generalist predators feeding on various insects such as flies, moths, grasshoppers, and beetles. They use speed rather than sticky silk to subdue prey.
Seasonal Activity
Most visible and active from mid-summer through early autumn (July to October), which coincides with their mating season.
Description
The Grass Spider is a common and fascinating sight in late summer landscapes. Known for their incredible speed, they create impressive horizontal silk sheets that act as vibration sensors. While often mistaken for more dangerous spiders, these are beneficial residents that provide excellent pest control.
Key Features
Two dark longitudinal stripes on the cephalothorax, very long and prominent dual-segmented spinnerets at the rear of the abdomen, and horizontal funnel web construction.
Similar Species
Wolf Spiders (Lycosidae) lack the long spinnerets and build no webs. Harsher-looking Hackledmesh Weavers (Amaurobiidae) lack the distinct stripes. Brown Recluse spiders lack any stripes or patterns on the abdomen/legs.
Life Cycle
Females lay egg sacs in late summer/autumn in sheltered crevices. Adults usually die in the first frost. Spiderlings overwinter inside the egg sac and emerge in the spring. Life span is roughly one year.
Ecological Importance
Significant biological control agents for garden and agricultural pests. They help regulate populations of flying and crawling insects in the immediate vicinity of homes.
Conservation Status
Not evaluated by IUCN, but considered stable and abundant throughout their range with no immediate threats.
Interesting Facts
The silk of their web is not sticky; the spider relies entirely on its lightning-fast reflexes to catch prey before it leaves the silk sheet. Despite their 'Grass' name, they are often found around window wells and door frames.
Photography Tips
Focus on the dorsal (top) view to capture the stripes and spinnerets. Because they are fast, photographing them while they are waiting at the mouth of their funnel web is usually the best approach.
Identified: 2026-07-10T23:26:08.993398