Wolf spiders (family Lycosidae) are active, ground-dwelling hunters found globally. Many species excavate and occupy burrows, though not all do. These spiders are characterized by their robust, hairy appearance and rely on speed and eyesight to chase down prey, rather than using a web for capture. Their varied environments have led to a range of survival strategies, including the use of underground shelters.
Burrowing vs. Wandering Life Cycles
Wolf spiders are categorized into two behavioral groups: sedentary burrowers and nomadic wanderers. This difference represents an evolutionary trade-off between energy expenditure and safety. Nomadic species, such as those in the genus Pardosa, spend most of their lives roaming and hunting. They often use temporary shelter under rocks or leaf litter and rely on speed and camouflage.
Sedentary species, notably those in the genus Geolycosa and some Hogna, are “obligate burrowers” that spend the majority of their lives in a fixed location. These spiders rarely stray far from their tunnels, retreating into them at the slightest sign of danger. While burrow construction requires a higher initial energy investment, it offers the long-term benefits of a climate-controlled refuge and a secure hunting perch. Males are the exception, eventually abandoning their burrows to wander in search of mates.
Construction and Function of Wolf Spider Burrows
The burrows of sedentary wolf spiders are typically vertical, tubular structures that can reach depths of 15 to 30 times the spider’s body length. The spider uses its chelicerae (jaws) and fangs to loosen the soil. It then compacts the substrate into a pellet (bolus) with its pedipalps. This pellet is carried to the surface and flung away from the entrance, or sometimes incorporated into the rim structure.
Burrowing species reinforce the inside walls of the tunnel with a thin layer of silk, which provides stability and prevents collapse in loose soil. Some spiders, particularly those in arid environments, construct a “turret” or silk collar at the entrance using silk, soil, and debris. This structure serves several functions: it prevents floodwater and debris from entering, acts as a subtle trip-wire to detect passing prey, and aids in thermoregulation. The burrow itself provides security from predators and offers a stable microclimate important for temperature regulation and avoiding desiccation.
Key Physical Traits for Identification
Wolf spiders are easily distinguished by their unique three-row eye arrangement. The bottom row consists of four small eyes, while the middle row contains two much larger, forward-facing eyes. A third row, positioned on the top of the head, holds two medium-sized eyes. This configuration gives them exceptional eyesight, crucial for their hunting lifestyle.
Wolf spiders are generally stout, with a robust body and strong, spiny legs that enable their speed. Their bodies are covered in coarse, dense hairs, giving them a fuzzy appearance. A characteristic behavior of the females is their unique maternal care method: they carry a spherical, silken egg sac attached to their spinnerets. Once the spiderlings hatch, they instinctively climb onto the mother’s back, where she carries them for several weeks until they disperse.