Grass Spider, Funnel Weaver
Agelenopsis aperta or similar Agelenidae species
Agelenidae (Funnel-Weavers), Order Araneae. Key family characteristics include three pairs of spinnerets with the posterior pair notably elongated, and a distinctive sheet web ending in a tubular retreat.
Physical Description
The spider has a relatively elongated body with a tapering, pointed abdomen and a distinct cephalothorax marked by characteristic dark longitudinal stripes on the dorsal carapace. The texture appears moderately hairy.
Size Estimate
Body length approximately 10 to 18 millimeters with a leg span reaching up to 30 to 50 millimeters, typical for an adult female or subadult funnel weaver.
Coloration & Markings
Predominantly brown and grayish tones with prominent dark longitudinal stripes running along the cephalothorax and pale lateral bands bordering a darker cardiac mark on the abdomen.
Web Type
Sheet web or funnel web. It builds a flat, horizontal, non-sticky sheet web close to the ground in grass or crevices, which funnels backward into a tubular retreat where the spider waits in ambush.
Eye Arrangement
Eight eyes arranged in two slightly curved rows of four, all relatively small and uniform in appearance, typical of the Agelenidae family.
Leg Characteristics
Long, tapering legs equipped with distinct spines, typical of active running spiders. The legs are held sprawled out on the flat web surface, ready for rapid sprinting.
Venom & Safety Information
Venom Information
Neurotoxic and proteolytic venom designed to immobilize small insect prey rapidly. It has very low toxicity to humans and large mammals.
Medical Significance
Not medically significant. Bites are rare, typically no more painful than a mild bee sting, and generally only cause localized redness and minor swelling.
Safety Recommendations
Keep lawns trimmed and vegetation cleared away from building foundations. If found indoors, gently guide the spider into a container using a piece of card and release it outdoors.
Habitat & Behavior
Habitat & Range
Widely distributed across North America in grassy fields, lawns, gardens, shrubbery, and occasionally around the foundations of human buildings.
Behavior & Temperament
Extremely fast runners and timid ambush predators. They retreat instantly into their funnel when disturbed, only biting if trapped or heavily pressured.
Diet & Prey
Primarily carnivorous, feeding on a wide variety of crawling and flying insects such as crickets, grasshoppers, flies, and beetles that land on their sheet webs.
Seasonal Activity
Most active during late spring, summer, and early autumn, with mature males wandering in search of females toward the end of the warm season.
Description
The grass spider is a quintessential backyard inhabitant, instantly recognizable by the intricate, sheet-like webs it weaves across lawns and bushes. Though lightning-fast and startling when they dart away, these shy hunters play a crucial ecological role in keeping insect populations in check without posing any real danger to humans.
Key Features
Elongated spinnerets visible at the rear of the abdomen, dark longitudinal stripes on the cephalothorax, and construction of a flat sheet web ending in a funnel-shaped retreat.
Similar Species
Wolf spiders (Lycosidae) which do not build webs, and funnel-web spiders of the family Atracidae, though the latter are restricted to Australia and are highly dangerous.
Life Cycle
Females construct silk egg sacs in protected crevices or near the web in late autumn, where eggs overwinter before spiderlings hatch in spring to disperse via ballooning or running.
Ecological Importance
Acts as an effective biological control agent by regulating populations of herbivorous and nuisance insects in lawns, gardens, and agricultural settings.
Conservation Status
Not evaluated by the IUCN, but populations are generally abundant, widespread, and stable across their natural ranges.
Interesting Facts
Grass spiders possess some of the fastest acceleration rates among terrestrial animals when sprinting across their webs to capture entangled prey.
Photography Tips
Use a macro lens with a fast shutter speed to capture details of the cephalothorax stripes. Photograph from above while keeping a respectful distance to avoid startling the spider back into its retreat.
Identified: 2026-08-21T03:58:51.026612