Scytodidae

Spitting spiders are most reliably identified by the combination of six eyes arranged in three pairs (two triads) and a conspicuously convex, domed cephalothorax. The eye arrangement distinguishes them from most other spider families, which typically have eight eyes. They may be confused with recluse spiders (Sicariidae), which also have six eyes in a similar triad pattern, but spitting spiders lack the characteristic violin-shaped marking on the cephalothorax found in many Loxosceles species and possess a much more pronounced domed cephalothorax. The long-legged species resemble cellar spiders (Pholcidae) but have only six eyes and the distinctive cephalothoracic shape. Web-building species construct tangled, sheet-like webs similar to those of Pholcidae, but can be distinguished by eye count and body proportions. Examination of genitalia is required for species-level identification: females have a simple gonopore accessed through the epigastric furrow, while males possess relatively simple pedipalps compared to entelegyne spiders.

Spitting spiders occupy diverse habitats including leaf litter, under rocks and bark, on vegetation, and in human structures. Long-legged species frequently inhabit the exterior of buildings, window frames, and eaves, where they construct tangled sheet webs. Short-legged species are ground-dwelling, found in leaf litter and under stones. Some species are known from forest edges, pine woodlands, and subtropical regions. Several species have been introduced to new regions through human activity and have become established in and around human habitations. In tropical regions, some species exhibit social behavior with multiple females and immatures cohabiting in shared retreats.

Cosmopolitan distribution with greatest diversity in tropical regions. The family occurs on every continent except Antarctica. Scytodes thoracica is the most widely distributed species in North America, ranging from Canada southward to at least Missouri and Iowa. Multiple species occur in the Caribbean, with records from Cuba, Dominican Republic, Puerto Rico, Jamaica, and numerous Lesser Antilles islands. The family is well-represented in Southeast Asia, with documented social behavior in Singapore. New species continue to be described from China, Algeria, and other regions. Several species have been introduced to areas outside their native ranges, including Scytodes longipes in North America.

Activity patterns vary by species and climate. In temperate regions, adults are encountered primarily in summer and fall. In tropical and subtropical regions, activity may occur year-round. Males wander to seek mates, making them more visible during breeding periods. Egg sacs are produced seasonally, with late summer and autumn records common in temperate zones.

Spitting spiders are generalist predators that feed on insects and other arthropods. They are known to prey on flies, moths, and other small insects attracted to lights. Some species are araneophagic, actively hunting and consuming other spiders. The unique venom projection mechanism allows them to capture prey that would otherwise escape, including spiders on their own webs. Prey is immobilized by the sticky venom threads, then subdued with a bite. Social species have been observed engaging in cooperative prey capture on large items, with multiple individuals spitting, biting, and feeding together. Scavenging behavior has also been documented.

Females wrap eggs in a thin sheet of silk and carry the egg sac beneath the body using their chelicerae, rather than constructing an elaborate suspended egg sac. Clutch size averages 20–40 eggs. Spiderlings remain in the mother's web until the fourth instar (after the third moult) in social species, though they become increasingly aggressive and cannibalistic toward conspecifics after the third instar. Development includes multiple instars before reaching maturity; immature spiders cannot be reliably identified to species due to undeveloped genitalia. Males reach maturity and wander to find mates. Lifespan and generation time vary by species and environmental conditions.

The defining behavior of spitting spiders is the projection of sticky venom from the fangs to immobilize prey. This attack lasts approximately 30 milliseconds and involves rapid oscillation of the jaws to create a zigzag pattern of glue threads that solidify upon contact, contracting up to 50% to bind prey tightly. Spitting spiders stalk prey with slow, deliberate movements before striking. Long-legged species construct tangled, sheet-like webs and may live communally; short-legged species are wandering hunters that do not build webs. Social species exhibit extended maternal care, with females provisioning spiderlings with prey and tolerating their presence through multiple instars. Multiple females may cooperate in guarding egg sacs, including foreign egg sacs that are adopted. Cooperative prey capture occurs on large prey items. Cannibalism among juveniles increases with age and is not apparently influenced by adult presence or prey abundance.

Spitting spiders function as generalist predators in their ecosystems, controlling populations of small insects and other arthropods. Their unique prey capture mechanism allows them to exploit prey unavailable to other predators, including spiders on webs. Some species serve as hosts for parasitoid wasps in the family Platygastridae. Social species may have more complex ecological interactions due to cooperative behaviors and communal living. In human-associated habitats, they contribute to control of pest insects attracted to lights.

Spitting spiders are not considered dangerous to humans despite their enlarged venom glands; their venom is specialized for prey capture rather than defense. They are sometimes mistaken for brown recluse spiders (Loxosceles) due to similar eye arrangements, causing unnecessary concern. Several species have become established in and around human habitations, particularly in warm climates, where they may be encountered on building exteriors and window frames. They are generally considered beneficial due to their predation on insects and other spiders. No significant medical importance has been documented, though isolated unverified reports of bites exist.

• Sicariidae (recluse spiders)Both families have six eyes in three pairs (two triads), but Sicariidae typically have a violin-shaped marking on the cephalothorax and lack the pronounced domed shape of Scytodidae
• Pholcidae (cellar spiders)Long-legged Scytodidae species resemble Pholcidae in body proportions and web structure, but Pholcidae have eight eyes and a flatter cephalothorax

Spitting spiders are sometimes mistaken for dangerously venomous brown recluse spiders due to similar eye arrangements, leading to unnecessary fear and extermination. Despite their enlarged venom glands and specialized prey-capture mechanism, they are not harmful to humans. The common name 'spitting spider' may suggest expectoration of venom, but the mechanism actually involves forcible ejection from the fangs rather than true spitting.

• spitting spiders
• venom projection
• social spiders
• haplogyne
• six-eyed spiders

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Bug Eric: Spider Sunday: Spitting Spiders
• Bug Eric: Spider Sunday: Spider Sex Ed
• Bug Eric: 2011
• Social behaviour of spitting spiders (Araneae: Scytodidae) from Singapore
• New records of spiders: Araneae, Eresidae, Cheiracanthiidae, Scytodidae from Pakistan
• On the Antillean spiders of the genus Scytodes Latreille, 1804 (Araneae, Scytodidae)
• Cosmopolitan Distribution of the Spitting Spider Scytodes thoracica Latreille, 1802 (Aranei, Scytodidae) and its New Findings of this Species in the Northern Parts of the Range
• Feeding ecology of the tropical spitting spider Scytodes longipes (Araneae, Scytodidae)
• Field Studies on the Biology of Loxosceles arizonica Gertsch and Mulaik (Araneae, Scytodidae)
• Studies on Scytodes Univittata Simon (Scytodidae: Arachnida) with Special Notes on its Biology
• A new spider species of Scytodes Latreille, 1804 from Jiangxi Province, southern China (Araneae, Scytodidae)
• A new species of Scytodes from Algeria (Araneae: Scytodidae), with a review of the species from the Maghreb
• Scavenging behavior in spitting spiders,Scytodes(Araneae: Scytodidae)
• Parental and predatory behaviour of Scytodes sp., an araneophagic spitting spider (Araneae: Scytodidae) from the Philippines
• Two new species of Idris Foerster (Hymenoptera: Platygastridae) from Southeastern Brazil parasitoids of Argyrodes elevatus Walckenaer (Araneae:Theridiidae) and Scytodes sp. (Araneae: Scytodidae)