Grass Spider, American Grass Spider, Funnel Weaver
Agelenopsis sp. (likely Agelenopsis pennsylvanica or Agelenopsis potteri)
Agelenidae (Funnel Weavers), Order Araneae. Characterized by long spinnerets and horizontal sheet webs.
Physical Description
A medium-sized spider with an elongated, pear-shaped cephalothorax and an oval abdomen. The body is covered in fine, bristly hairs. A prominent feature is the pair of long, two-segmented spinnerets protruding from the rear of the abdomen.
Size Estimate
Body length: 10-20mm for females. Leg span: approximately 30-50mm. This appears to be an adult female based on body proportions.
Coloration & Markings
Tan to grayish-brown base color. The cephalothorax features two dark longitudinal stripes. The abdomen contains a central light band bordered by darker, mottled patterns and small spots.
Web Type
A horizontal, non-sticky sheet web that tapers into a silken funnel retreat in one corner. These webs are often built on low-lying shrubs or grass.
Eye Arrangement
Eight eyes arranged in two rows of four, with both rows being strongly procurved (curving forward), creating a pattern that looks roughly like three rows (2-4-2).
Leg Characteristics
Long, slender legs with conspicuous spines (macrosetae). They are typically the same color as the body, sometimes showing faint banding or darker distal segments.
Venom & Safety Information
Venom Information
Possesses minor neurotoxic venom used to paralyze insect prey. The venom is not considered medically significant to humans.
Medical Significance
Low danger. Bites are rare due to their shy nature. Symptoms are usually localized and milder than a bee sting, involving slight swelling, itching, or redness. No specialized treatment is required.
Safety Recommendations
Harmless and beneficial. If found indoors, they can be easily relocated using a cup and card. Wear gloves when gardening in thick brush to avoid accidental defensive nips.
Habitat & Behavior
Habitat & Range
Common throughout North America (USA and Canada). They are found in gardens, tall grass, low shrubs, and occasionally near window wells or door frames.
Behavior & Temperament
Very fast runners. They wait in the funnel retreat for vibrations and dash out to grab prey on the sheet. They are generally shy and will retreat rapidly if disturbed; they are not aggressive toward humans.
Diet & Prey
Generalist predators feeding on various insects that land on the web sheet, including flies, grasshoppers, moths, and beetles. They use speed rather than sticky silk to capture prey.
Seasonal Activity
Most visible in late summer and early autumn when webs are largest and males are wandering to find mates. Dew on autumn mornings often highlights their massive sheets.
Description
The Grass Spider is a quintessential backyard inhabitant. Recognizable by its remarkable speed and architecturally distinct funnel-shaped webs, it serves as a master of ambush. Its earthy tones provide perfect camouflage among dried leaves and vegetation.
Key Features
Prominent long spinnerets at the tail end, two dark racing stripes on the cephalothorax, and the characteristic horizontal sheet web with a funnel retreat.
Similar Species
Often confused with Wolf Spiders (Lycosidae), but Wolf Spiders do not build webs and have different eye arrangements. Also similar to the Hobo Spider (Eratigena agricola), which lacks the long spinnerets.
Life Cycle
Females lay egg sacs in late summer or autumn in protected crevices. The mother usually dies before winter, and spiderlings emerge in the spring. They have a one-year lifespan.
Ecological Importance
Critical for natural pest control in gardens and landscapes, consuming large quantities of insects that might otherwise damage plants or enter homes.
Conservation Status
Not evaluated by IUCN, but considered common and stable throughout their range with no significant threats.
Interesting Facts
Grass spider silk is not sticky. Instead, the spider relies on its extreme agility and the trip-wire nature of the sheet's surface to detect and run down prey before it can escape.
Photography Tips
Photograph from above to capture the cephalothorax stripes and spinnerets. Early morning is the best time when dew makes the web visible and provides a dramatic background.
Identified: 2026-07-12T19:07:11.139343