Yellow Sac Spider, Long-legged Sac Spider
Cheiracanthium inclusum (or Cheiracanthium mildei)
Miturgidae (Sac Spiders), Order Araneae. Key family characteristics include eight similar eyes in two rows and conical anterior spinnerets.
Physical Description
Small to medium-sized spider with a pear-shaped abdomen, oval cephalothorax, and slightly elongated proportions. The texture is relatively smooth with fine hairs.
Size Estimate
Body length typically ranges from 5 to 10 mm, with a leg span of around 20 to 25 mm. The specimen appears to be an adult or sub-adult.
Coloration & Markings
Pale yellow, beige, or light greenish-tan body with a slightly darker dorsal stripe running along the abdomen. Lacks complex patterns.
Web Type
Does not build traditional orb webs. Constructs a silken retreat or sac (usually in corners, under leaves, or behind objects) where it rests during the day.
Eye Arrangement
Eight eyes of roughly equal size arranged in two fairly straight horizontal rows across the front of the cephalothorax.
Leg Characteristics
The first pair of legs is noticeably longer than the others, which is a characteristic feature of sac spiders. Legs are relatively slender and unmarked.
Venom & Safety Information
Venom Information
Contains a mild cytotoxic venom used to subdue insect prey. Envenomation in humans is typically mild and non-lethal.
Medical Significance
Low medical significance. Bites can cause localized pain, redness, and mild swelling, occasionally compared to a mild wasp sting, but severe necrotic reactions are rare and often debated.
Safety Recommendations
Shake out clothing and shoes left on the floor. If found inside, gently capture it in a container and release it outdoors away from living areas.
Habitat & Behavior
Habitat & Range
Found worldwide in temperate and tropical regions. Prefers foliage, gardens, orchards, and frequently wanders indoors into homes and buildings.
Behavior & Temperament
Nocturnal hunter that actively forages for prey at night. Can be defensive if trapped or cornered against the skin.
Diet & Prey
Feeds on a wide variety of small insects and other spiders, actively hunting them down rather than trapping them in a web.
Seasonal Activity
Most active during the warm spring and summer months, often moving indoors in late autumn as temperatures drop.
Description
The yellow sac spider is a common nocturnal hunter frequently encountered in residential areas. Known for its pale coloration and distinctive long front legs, it spends daylight hours hidden inside small silken tubes.
Key Features
Pale yellow-green coloration, noticeably elongated first pair of legs, and the habit of resting inside a silken retreat sac.
Similar Species
Other pale-colored wandering spiders, such as ghost spiders (Anyphaenidae) or juvenile huntsman spiders, which can be distinguished by specific eye arrangements and spinneret structures.
Life Cycle
Females construct silk egg sacs in protected areas during spring or summer, guarding the eggs until hatching. Undergoes multiple molts to reach maturity with a lifespan of about one year.
Ecological Importance
Acts as an effective generalist predator in agricultural fields and gardens, helping control populations of herbivorous insect pests.
Conservation Status
Not evaluated by the IUCN, but populations are secure, widespread, and highly adaptable.
Interesting Facts
Yellow sac spiders are frequently blamed for necrotic spider bites, though modern toxicology suggests their venom is only mildly cytotoxic and many attributed bites are actually from other sources.
Photography Tips
Use macro lighting and a steady hand or tripod. Focus on the eye arrangement and the distinctively long front legs for accurate identification.
Identified: 2026-08-21T02:37:15.675778