Complete Guide To The Grass Spiders

Grass Spider Notes

• Grass spiders are common in grassy areas throughout North Carolina. They are especially obvious on suburban lawns or in urban parks where turf grass is maintained as part of human landscaping.
• These spiders build large sheet webs that drape across the grass. The webs include a narrow, funnel-like section that dips between blades of grass.
  • Unlike the capture spiral strands spun by Orb Weaver Spiders, the webs spun by grass spiders aren’t sticky and can’t trap or hold prey. Instead, the strands act like trip wires and remote sensors.
  • The web strands vibrate when touched by passing insects. The vibrations transmit down the web lines to the waiting spider who rushes out to attack.
  • Grass spiders are remarkably fast sprinters. They bite prey immediately on contact, with none of the delicate maneuvering seen in other spiders who can rely on their webs to restrain prey temporarily. Grass spiders must rely on speed and their ability to immobilize prey quickly. Otherwise, their prey would escape.
• Unlike so many wild animals, grass spiders may be a species that benefits from human presence and environmental engineering. A study that researched the abundance and distribution of Agelopsis pennsylvanica (also a North Carolina spider species). The researchers found more spiders in the urban center, represented by a university campus, than in an urban forest, represented by a city park.
  • However, abundance decreased with increased road traffic, possibly due to the vibrations caused by the contact of car tires with the ground (Pessman et al. 2023, https://doi.org/10.1007/s11252-023-01379-z). Grass spiders rely on vibratory signals that transmit through their web lines. They use vibration to find prey, court potential mates, and evade predators. Vibrations from road noise can potentially swamp the more subtle signals grass spiders need to sense.
• A gentle brush against their sheet webs can sometimes tempt Grass Spiders to peek out of their funnels. But forceful contact will scare the spider into flight. The funnels open into the grass, which conceals fleeing spiders.