Are daddy long leggs poisonous

No. According to many entomologists they are not. These are insects and are not even true Spiders. This rumor has been all around the place making these critters seem more dangerous than they really are. As one of my professors had said, "It is really hard to be the most poisonous spider in the world when you have no venom." There are many sites you can visit on entomology. Just search Opiliones or Harvestmen.