The common question about “granddaddy long legs” is whether they are poisonous. This widespread misconception has led many to believe these arthropods pose a hidden danger. Understanding their true nature requires clarifying what “granddaddy long legs” refers to and dispelling these fears.
Identifying “Granddaddy Long Legs”
The common name “granddaddy long legs” refers to two distinct arachnids, causing much confusion. One group is harvestmen (order Opiliones), which are not true spiders. Harvestmen have a single, fused body segment, giving them a compact, oval appearance. They typically possess two eyes and lack silk glands, so they do not spin webs. Their mouthparts are designed for chewing, not biting with fangs.
The other animal often called “granddaddy long legs” is the cellar spider (family Pholcidae). These are true spiders, characterized by two distinct body segments and typically eight eyes. Cellar spiders are known for their extremely long, thin legs and small bodies, often found spinning loose, messy webs in corners of basements and other sheltered areas. Unlike harvestmen, cellar spiders possess fangs and venom glands.
Dispelling the Poison Myth
The myth that “granddaddy long legs” are highly venomous but cannot bite humans is largely untrue for both types. Harvestmen (Opiliones) are harmless to humans because they do not possess venom glands or fangs. While they may release a foul-smelling fluid as a defense mechanism, this substance is not venomous or poisonous to humans.
Cellar spiders, while true spiders and thus venomous, do not have venom that is medically significant to humans. Their fangs are notably small, measuring approximately 0.25 millimeters. Human skin thickness generally ranges from 0.5 to 4 millimeters, meaning their fangs are often too short to effectively penetrate skin. Even if a bite occurs, it typically results in mild, localized irritation with no lasting health consequences. Cellar spiders primarily use silk to immobilize prey, rather than relying on venom for larger targets.
Coexisting with Granddaddy Long Legs
Both harvestmen and cellar spiders play beneficial roles in their environments, making them valuable residents. Harvestmen are important decomposers, helping break down decaying plant and animal matter. They also act as generalist predators, feeding on small insects, mites, and other invertebrates.
Cellar spiders are effective predators of various household pests. They actively hunt and consume small insects like mosquitoes, flies, and gnats that become entangled in their webs. These spiders also prey on other spider species, including brown recluse and black widows, by wrapping them in silk. Given their shy nature and lack of danger to humans, there is no need to remove them from homes or gardens.