Tube Web Spider, Cellar Spider
Segestria florentina
Segestriidae (Tube Web Spiders), Order Araneae
Physical Description
A robust spider with a cylindrical body. The cephalothorax is dark and elongated, while the abdomen is cigar-shaped. A key anatomical feature is having the first three pairs of legs directed forward.
Size Estimate
Body length typically 15-22mm for females; leg span can reach 50-60mm. This specimen appears to be a large mature adult.
Coloration & Markings
Mostly black or dark brown. Mature individuals often display iridescent green chelicerae (fangs). The abdomen may have a faint pattern of darker spots or chevrons.
Web Type
Tubular web built in crevices with radiating trip-wires. Usually placed in walls, bark, or window frames.
Eye Arrangement
Six eyes arranged in three pairs (dyads) in a semi-circle across the front of the cephalothorax.
Leg Characteristics
First three pairs of legs are oriented forward (prograde) to facilitate movement in tunnels. Legs are thick and darkly colored.
Venom & Safety Information
Venom Information
Neurotoxic venom, though relatively mild compared to medically significant spiders. It contains segestritoxins which affect sodium channels.
Medical Significance
Bite is painful (similar to a bee sting) and may cause local swelling or numbness for several hours, but is not considered life-threatening to healthy humans.
Safety Recommendations
Avoid handling with bare hands due to the painful bite. Use a cup and stiff paper to relocate the spider outside into a wall crack or garden area.
Habitat & Behavior
Habitat & Range
Common in Europe and the Mediterranean; introduced to parts of South America and Australia. Often found in old masonry, walls, and under tree bark.
Behavior & Temperament
Nocturnal ambush hunter. They wait at the entrance of their tube for prey to touch the trip-wires. They are defensive and can be aggressive if provoked or squeezed.
Diet & Prey
Insects, woodlice, and even other spiders. They strike rapidly, dragging prey into the tube web.
Seasonal Activity
Active year-round in warmer climates, but most visible in late summer and autumn during mating season.
Description
A formidable-looking dark spider that is easily identified by its unique leg positioning. While they appear scary, they are beneficial hunters of household pests.
Key Features
Three pairs of legs pointing forward, iridescent green fangs, and a long cylindrical abdomen.
Similar Species
May be confused with Black Lace-weavers (Amaurobius ferox) or larger Wolf Spiders, but the leg orientation is a diagnostic differentiator.
Life Cycle
Females stay with their eggs in the tube. Upon hatching, spiderlings may stay with the mother for several molts. Lifespan is typically 1-2 years.
Ecological Importance
Significant predator of urban pests like cockroaches and woodlice, maintaining a balance in synanthropic environments.
Conservation Status
Not evaluated by IUCN, but common and widespread in its native and introduced range.
Interesting Facts
The iridescent green on their fangs is produced by structural coloration rather than pigment, designed to signal to mates or deter predators.
Photography Tips
A macro lens is needed to capture the green iridescence of the fangs. Side-on shots show the cylindrical body shape best.
Identified: 2026-06-01T21:33:39.625850