How to call a mama "daddy longlegs spider"?? Hmmm.......
There is an urban legend stating that daddy long-legs spiders have the most potent venom of any spider, but that their chelicerae (fangs) are either too small or too weak to puncture human skin; the same legend is also repeated of the harvestman and crane fly, also called "daddy long-legs" in some locales. Indeed, pholcid spiders do have a short fang structure (called uncate). However, brown recluse spiders also have uncate fang structure, but are able to deliver medically significant bites. Either pholcid venom is not toxic to humans or there is a musculature difference between the two arachnids, with recluses, being hunting spiders, possessing stronger muscles for fang penetration.
In 2004, the Discovery Channel show MythBusters set out to test the daddy long-legs myth episode 13 - "Buried in concrete". Hosts Jamie Hyneman and Adam Savage first established that the spider's venom was not dangerously toxic by injecting it into a mouse, which showed no ill effects. After measuring the spider's fangs at approximately 0.25 mm (average human skin thickness varies from about 0.5mm to 4mm), Adam Savage allowed himself to be bitten, and reported that the bite produced little more than a mild short-lived burning sensation. This appears to confirm that, contrary to popular belief, pholcid bites can penetrate human skin but will deliver a harmless envenomation. Additionally, recent research by Alan Van Dyke has shown that pholcid venom is relatively weak in its effects on insects as well.
According to Rick Vetter of the University of California at Riverside, the daddy long-legs spider has never harmed a human and there is no evidence that they are dangerous to humans.
The urban legend ostensibly stems from the fact that the daddy long-legs spider is known to prey upon deadly venomous spiders, such as the redback, a member of the black widow genus Latrodectus. By extrapolation, it was thought that if the daddy long-legs spider could regularly kill a spider capable of delivering fatal bites to humans, then it must be more venomous, and the uncate fangs were accused of prohibiting it from killing people. In reality, it is merely quicker than the redback.