The common belief that “daddy longlegs” possess potent venom but cannot bite humans is a widespread misconception. This popular term actually refers to at least two distinct types of arachnids, leading to confusion about their true nature. Understanding each group’s unique characteristics helps clarify the facts.
Harvestmen: The True “Daddy Longlegs”
One group commonly known as “daddy longlegs” are harvestmen, belonging to the order Opiliones. Unlike spiders, harvestmen do not possess venom glands or fangs capable of injecting venom into humans. Their bodies appear as a single, oval structure, lacking the distinct two-part segmentation seen in true spiders. Harvestmen have pincer-like mouthparts, called chelicerae, which they use for grasping and tearing food.
These arachnids are primarily omnivorous, consuming a diverse diet that includes small insects, mites, plant material, fungi, and even bird droppings. They also act as scavengers, feeding on dead organisms. When disturbed, some species may emit a foul-smelling chemical as a defense mechanism, rather than relying on venom.
Cellar Spiders: The Other Contender
Another group frequently called “daddy longlegs” are cellar spiders, which are true spiders belonging to the family Pholcidae. These spiders do possess venom glands and fangs, like most other spiders. However, their venom is not considered medically significant or dangerous to humans. Research indicates their venom is relatively weak, only 1.9 percent the strength of brown recluse spider venom.
Cellar spiders have very short fangs, which typically struggle to penetrate human skin. While a bite might occur, the effect is typically a mild sting with no lasting effects. These spiders predominantly rely on their silk webs to immobilize prey, using their long legs to manipulate the silk and ensnare insects. They are commonly found indoors, creating loose, messy webs in corners of rooms, basements, and attics.
Beyond the Myth: Their Role in Ecosystems
Both harvestmen and cellar spiders play beneficial roles within their respective ecosystems, extending beyond the misconceptions about their venom. Harvestmen contribute as decomposers, breaking down decaying organic matter and aiding in nutrient cycling in various habitats, including forests and grasslands. They also function as generalist predators, helping to control populations of soft-bodied insects like aphids and mites, which can be agricultural or garden pests.
Cellar spiders serve as effective natural pest controllers in human environments. They actively hunt and consume a variety of nuisance insects and other arthropods that become entangled in their webs. Their diet can include mosquitoes, gnats, flies, cockroaches, and even other spiders, including more venomous species like black widows and brown recluses. By preying on these organisms, cellar spiders help to maintain a balanced indoor environment, reducing the need for chemical pesticides.