Insects

Although most insects are relatively benign or innocuous, such as Fire Wasps, the nature of Tol is such that some present great threats to the average person. This can generally happen in one of three ways.
If an insect is exposed to magic and becomes giant, such as in the case of the relatively common Giant Ant, it can be a danger. Such creatures are generally simply carrying out their normal behaviors, such as food-gathering, but their size means they can consider Humans and other inhabitants of Tol as food.
Insects that are exposed to the energies of another plane can gain a malign nature. This is the case with such creatures as the Stormclaw Scorpion, whose exposure to the Elemental Chaos has made it more aggressive and infused it with lightning energies. It’s also true in the case of the blessedly rare Hellstinger Scorpions and Hellwasps, which are usually found in Hell but which can sometimes end up on Tol proper.
A third possible danger comes when insects engage in the bizarre behavior knowing as Swarming. Some philosophers and sages believe that the influence of the Far Realm causes normally harmless insects to gather together in large numbers and begin a swarming behavior, acting almost as a single creature. Stories abound of how dangerous a swarm of Rot Grubs or Stirges can be, for example.