Most venomous?
There is an urban legend stating that daddy long-legs spiders have the most potent venom of any spider, but that their chelicera (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. [1]In 2004, the Discovery Channel show MythBusters set out to test the daddy long-legs myth (season 1, episode 13 “Buried in Concrete”). After measuring the spider’s fangs at approximately 0.25 mm (average human skin thickness varies from about 0.5mm to 4mm), the show’s host was apparently bitten, although the bite produced little more than a mild short-lived burning sensation. This appears to confirm the suspicion that pholcids can penetrate human skin, but that their venom is practically harmless to humans. Additionally, recent research by Alan Van Dyke has shown that pholcid venom is actually relatively weak in its effects on insects as well[5].According to the University of California at Riverside, the daddy long-legs spider has never harmed a human and there is no proof that they are venomous to humans.[6]One reason why these spiders are said to be so dangerous could be that they regularly prey on other spiders, including the black widow (Latrodectus spp.), which itself can be dangerous to humans, with the reasoning that the preying spider must be even more venomous; which is incorrect. (Pinto-da-Rocha et al. 2007:4)
Pholcidae - Wikipedia, the free encyclopedia