Definition
The grass spider is a common name for several species of funnel‑web constructing spiders in the family Agelenidae, particularly those of the genus Agelenopsis found in North America.
Overview
Grass spiders are primarily terrestrial arachnids that inhabit grassy fields, lawns, gardens, and low vegetation across much of the United States and southern Canada. They are known for building flat, sheet‑like webs with a funnel retreat at one end, typically positioned close to the ground among grasses or low shrubs. These spiders are active hunters; when prey contacts the sheet, the spider darts from the funnel to capture it. Adults are most frequently observed from late spring through early autumn.
Etymology / Origin
The common name “grass spider” derives from the spider’s preferred habitat—grassland and low‑lying vegetation—and its frequent occurrence in such environments. The term is a straightforward descriptive compound in English, without a known historical or literary origin beyond this ecological association.
Characteristics
- Taxonomy: Family Agelenidae; genus Agelenopsis (e.g., Agelenopsis aperta, A. emertoni, A. georgilis).
- Size: Adults typically range from 7 to 15 mm in body length, not including leg span.
- Morphology: Dorsal coloration varies from light brown to gray, often with darker longitudinal stripes on the abdomen. The cephalothorax is relatively flat, and the legs are long and slender, adapted for rapid movement.
- Web Structure: A horizontal sheet of non‑sticky silk anchored to vegetation, with a conical funnel retreat on one side where the spider hides.
- Behavior: Primarily nocturnal; relies on vibration sensing to detect prey on the sheet. Mating occurs in late summer, with males approaching the female’s funnel retreat. Females lay egg sacs containing dozens to hundreds of eggs; spiderlings emerge after several weeks.
- Venom: Like most Agelenidae, grass spiders possess venom that subdues small insects. Their bite is not considered medically significant to humans, causing at most mild local irritation.
Related Topics
- Funnel‑web spiders (family Agelenidae) – the broader family to which grass spiders belong.
- Sheet web – the type of web constructed by grass spiders.
- Ground‑dwelling spiders – ecological category including many species that inhabit low vegetation.
- Arachnology – the scientific study of spiders and related arthropods.
- Other common names – “American grass spider,” “desert grass spider” (referring to specific Agelenopsis species).