Desert Grass Spider, Funnel Weaver
Agelenopsis aperta
Agelenidae (Funnel-Weavers), Order Araneae
Physical Description
Elongated oval abdomen, distinct cephalothorax with dark longitudinal stripes, and notably long spinnerets protruding from the rear of the abdomen. The body is covered in fine setae.
Size Estimate
Body length typically ranges from 10 to 20 mm, with a leg span reaching up to 40 to 50 mm.
Coloration & Markings
Grey to brown base coloration with distinctive dark brown or black longitudinal bands running along the dorsal side of the cephalothorax and sides of the abdomen.
Web Type
A flat, horizontal sheet web that funnels into a tubular retreat where the spider hides, non-sticky silk.
Eye Arrangement
Eight eyes arranged in two distinct rows, typically uniform in size and closely spaced in a slightly recurved or straight line.
Leg Characteristics
Long, tapering legs with prominent spination, held flat against the surface in a spread posture ready for rapid acceleration.
Venom & Safety Information
Venom Information
Neurotoxic venom used to quickly subdue insect prey, generally mild and ineffective against human skin.
Medical Significance
Not medically significant. Bites are extremely rare, non-lethal, and usually result in only minor local irritation comparable to a mild ant sting.
Safety Recommendations
Harmless to humans; simply leave them be or gently guide them outside if found indoors using a container.
Habitat & Behavior
Habitat & Range
Western North America, found in arid and semi-arid regions, grasslands, and gardens, constructing webs near the base of grasses, rocks, or shrubs.
Behavior & Temperament
Extremely fast runners, highly alert, and timid; they retreat into their funnels at the slightest disturbance.
Diet & Prey
Insects such as grasshoppers, beetles, flies, and caterpillars trapped on the sheet web.
Seasonal Activity
Most active during late spring through autumn, with mating occurring in late summer and early fall.
Description
The Desert Grass Spider is a master of structural engineering in the mini-ecosystem of the lawn or shrubbery. Lurking within a characteristic funnel-shaped retreat at the edge of a non-sticky sheet web, this agile hunter rushes out at lightning speed to intercept any unfortunate insect that steps onto its silken platform.
Key Features
Prominent, elongated spinnerets at the rear of the abdomen and a distinct funnel-shaped web retreat.
Similar Species
Hobo Spider (Eratigena agrestis) and Wolf Spiders (Lycosidae); distinguished by the prominent spinnerets and web architecture.
Life Cycle
Females construct silken egg sacs in protected areas during autumn, overwinters as eggs or juveniles, maturing by the following summer.
Ecological Importance
Acts as an effective natural controller of insect populations in gardens and grasslands.
Conservation Status
Not evaluated by the IUCN, but populations are stable and widespread.
Interesting Facts
Grass spiders are among the fastest terrestrial invertebrates over short distances, using hydraulic pressure to extend their legs rapidly.
Photography Tips
Use a macro lens, approach slowly to avoid triggering their flight response into the funnel, and use natural side lighting to highlight the web texture.
Identified: 2026-10-01T20:53:48.832970