The question “are daddy long legs poisonous?” is common, often fueled by myths about potent venom and small fangs. This article clarifies the facts about these creatures and their potential threat, addressing prevalent misconceptions.
Unraveling the Myth
The notion that “daddy long legs” are highly venomous but unable to bite humans is a persistent urban legend. “Poisonous” implies harm if ingested, while “venomous” refers to harm from injected toxins. Cellar spiders (Pholcidae), often called “daddy long legs,” are venomous, like nearly all spiders. However, their venom is not medically significant to humans and is relatively mild.
Cellar spiders possess fangs and venom glands, but their fangs are quite short. While they can theoretically bite, such incidents are rare, and any bite usually results in a mild sting. The myth likely arose because cellar spiders prey on other spiders, including black widows, by entangling them with silk rather than relying solely on potent venom.
In contrast, harvestmen (Opiliones), another group commonly called “daddy long legs,” are not venomous. They lack venom glands and fangs, using their mouthparts for grasping and tearing food. Therefore, harvestmen pose no danger to humans.
Understanding “Daddy Long Legs”
The term “daddy long legs” causes confusion because it refers to three distinct types of arthropods. The most common is the cellar spider (Pholcidae), a true spider characterized by its small body and extremely long, thin legs. Cellar spiders typically have two body segments and eight eyes.
Another animal frequently called “daddy long legs” is the harvestman, which belongs to the order Opiliones. While also arachnids, harvestmen are not spiders. They have a single, oval-shaped body segment where the cephalothorax and abdomen are broadly joined, unlike the distinct two-segment body of spiders. Harvestmen also differ from spiders by lacking silk glands and not producing webs.
Finally, some people mistakenly refer to crane flies (Tipulidae) as “daddy long legs.” Crane flies are insects, not arachnids, and are easily distinguished by having six legs and wings. They resemble large mosquitoes but are entirely harmless to humans. Adult crane flies do not bite or sting and do not transmit diseases.
Ecological Role and Behavior
Cellar spiders play a beneficial role in indoor environments as predators. They primarily feed on small insects like flies, mosquitoes, and other flying pests that become ensnared in their webs. These spiders also prey on other spiders, including potentially dangerous species such as brown recluse spiders and black widows, which they subdue by wrapping them in silk. When disturbed, cellar spiders may rapidly vibrate their webs, a behavior believed to confuse or deter predators.
Harvestmen are often omnivorous, consuming a diverse diet that includes small insects, other arthropods, plant material, fungi, and decaying organic matter. Some species are generalist predators, while others act as scavengers, contributing to nutrient recycling in their ecosystems. Unlike spiders, harvestmen grasp their prey with their mouthparts rather than injecting venom. Harvestmen are generally docile and non-aggressive towards humans, preferring to escape when threatened. They possess defensive scent glands that can release a peculiar-smelling fluid or chemical compounds when disturbed, and some can shed a leg to distract a predator.