Many people wonder if the long-legged creatures known as “daddy long legs” are dangerous. This common term often leads to confusion about whether these animals are poisonous. Understanding their true nature can clarify their actual risk to humans.
The Two Creatures Known as “Daddy Long Legs”
The term “daddy long legs” refers to two distinct arachnids often mistaken for each other.
One group is harvestmen (Order Opiliones), which are not true spiders. These arachnids have a single, fused body segment. Some harvestmen can be reddish-brown or orange, and some may even carry red mites on their bodies.
The other is the cellar spider, a true spider (Family Pholcidae). Unlike harvestmen, cellar spiders have a distinct two-part body (cephalothorax and abdomen). They are characterized by incredibly long, thin legs, often several times their body length. Cellar spiders typically range from pale yellowish to light brown or gray, though some have a reddish-brown hue.
Are They Dangerous? Dispelling the Venom Myth
Harvestmen are harmless to humans, lacking venom glands and fangs. Their mouthparts are too small to break human skin. Therefore, any reddish appearance on a harvestman does not signify danger.
Cellar spiders do possess venom, but it is not medically significant to humans. Their fangs are small (around 0.25 mm), making it challenging to puncture human skin (0.5 to 4 mm thick). If a bite occurs, it usually results in only a mild, short-lived burning sensation or no noticeable effect. The urban legend that cellar spiders have potent venom but fangs too short to bite humans is inaccurate. This myth likely stems from observations of them preying on more dangerous spiders.
More Than Just “Poisonous”: Their Role and Behavior
Both harvestmen and cellar spiders are generally non-aggressive. Harvestmen are often found in moist, shady environments and may emit a defensive odor if disturbed. Cellar spiders are typically timid and will attempt to escape when confronted.
Cellar spiders serve as beneficial inhabitants in many homes due to their predatory habits. They construct loose, irregular webs and effectively capture a variety of small household pests, including mosquitoes, gnats, and flies. Cellar spiders are also known to prey on other spiders, even larger species like wolf spiders and venomous spiders. They achieve this by using their long legs to ensnare prey with silk, sometimes vibrating the webs of other spiders to lure them. This natural pest control capability makes them advantageous to have around.